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A developer supply cartridge supplies developer into a process cartridge and is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The process cartridge includes a drum, a developing roller, a receiving-side shutter opening and closing a developer receiving op

A developer supply cartridge supplies developer into a process cartridge and is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The process cartridge includes a drum, a developing roller, a receiving-side shutter opening and closing a developer receiving opening receiving the developer used by the roller, a receiving-side mover to move the shutter including an operator, and a regulator regulating movement of the mover when the operator is at an operating position. The developer supply cartridge includes a developer accommodator, developer supply opening supplying developer from the accommodator into the process cartridge through the developer receiving opening, a supplying-side shutter opening open and closing the developer supply opening, and a supplying-side mover to move the supplying-side shutter from a closed to an open position when the developer supply cartridge enters and the process cartridge is set in the main assembly, by engagement with the operator.

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What is claimed is: 1. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic phot

What is claimed is: 1. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by said developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion movable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of the receiving-side movable portion when the receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; and a supplying-side movable portion movable, when said developer supply cartridge enters the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, to interrelatedly move said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position by engaging the receiving-side operating portion of the receiving-side movable portion when the receiving-side operating portion is positioned at the operating position and the movement of the receiving-side operating portion is regulated by the regulating member. 2. A developer supply cartridge according to claim 1, further comprising an engageable member fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus, wherein when said developer supply cartridge enters the main assembly of the apparatus, said engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the regulating member regulates rotation of the receiving-side movable portion and the receiving-side shutter portion is placed at the developer-reception-preventing position to move the regulating member, thus permitting movement of the receiving-side movable portion and then said engageable member engages the receiving-side operating portion of the receiving-side movable portion to rotate the receiving-side movable portion, thus moving the receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position. 3. A developer supply cartridge according to claim 1, wherein said supplying-side movable portion is disposed on a lower surface of said developer supply cartridge in a state that said developer supply cartridge is mounted to the main assembly of the apparatus, and is rotatable about a horizontal axis crossing a longitudinal direction of said developer supply cartridge. 4. A developer supply cartridge according to claim 1, wherein said supplying-side shutter portion is disposed on a lower surface of said developer supply cartridge in a state that said developer supply cartridge is set in the main assembly of the apparatus and includes a rotatable member rotatable about a horizontal axis crossing a longitudinal direction of said developer supply cartridge, said rotatable member being provided with an opening which opens in a radial direction of rotation of said rotatable member, and wherein said developer supply opening is opened by said opening of said rotatable member being moved to oppose said developer supply opening, and said developer supply opening is closed by a portion of said rotatable member other than said opening being moved to oppose said developer supply opening. 5. A developer supply cartridge according to claim 1, wherein said supplying-side movable portion is rotatable, and said supplying-side movable portion includes a projection having a portion extending along a rotational movement direction of said supplying-side movable portion, and wherein the receiving-side movable portion is rotatable, and the receiving-side operating portion includes a projection having a portion extending along the rotational moving direction of the receiving-side movable portion, said projection of said supplying-side movable portion being engageable with the projection of the receiving-side movable portion to receive a rotating force, thus rotating said supplying-side shutter portion. 6. A developer supply cartridge according to claim 1, further comprising a portion to be guided having a side surface to be regulated, an upper surface to be regulated, and a lower surface to be regulated, wherein when said developer supply cartridge enters the main assembly of the apparatus, said side surface to be regulated, said upper surface to be regulated and said lower surface to be regulated are regulated by a main assembly guide provided in the main assembly of the apparatus, and wherein in a state that said supplying-side movable portion is moving in engagement with the receiving-side movable portion, an upward movement of said upper surface to be regulated is prevented by the main assembly guide. 7. A developer supply cartridge according to claim 1, wherein said supplying-side shutter portion comprises a shutter member having an opening, a connecting member, and a recess in said connecting member, wherein said supplying-side movable portion comprises a rotatable member and a projection extending from said rotatable member, and wherein said projection is press-fitted into said recess so that movement of said supplying-side movable portion moves said supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position. 8. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said process cartridge is capable of receiving a supply of a developer from a developer supply cartridge, wherein the developer supply cartridge includes a supplying-side developer accommodating portion for accommodating the developer, a supplying-side shutter portion movable between a developer-supply-permitting position for opening a developer supply opening for supplying the developer from the supplying-side developer accommodating portion into the process cartridge and a developer-supply-preventing position for closing the developer supply opening, a supplying-side movable portion movable to interrelatedly move the supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position, and an engageable member, said process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with the developer; a receiving-side developer accommodating portion for accommodating the developer; a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion; a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening; a regulating member; and a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a first receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-preventing position and a second receiving-side operating portion which takes the operating position when said receiving-side shutter portion is at the developer-reception-permitting position, wherein when said process cartridge enters the main assembly of the apparatus in a state that the developer supply cartridge is set in the main assembly of the apparatus, a) said regulating member regulates movement of said receiving-side movable portion to maintain said first receiving-side operating portion at the operating position, b) said regulating member then contacts the engageable member to release said receiving-side movable portion from regulation by said regulating member, thus permitting movement of said receiving-side movable portion, c) then said receiving-side movable portion moves said receiving-side shutter portion to the developer-reception-permitting position in interrelation with said first receiving-side operating portion being moved by contacting the engageable member, and d) then the movement of said receiving-side movable portion is again regulated by said regulating member, and said receiving-side movable portion. while being so regulated. moves the supplying-side shutter portion to the developer-supply-permitting position in interrelation with movement of the supplying-side movable portion by engagement of said second receiving-side operating portion at the operating position with the supplying-side movable portion. 9. A process cartridge according to claim 8, wherein said receiving-side movable portion is disposed on an upper surface of said process cartridge in a state that said process cartridge is mounted to the main assembly of the apparatus and is rotatable about a horizontal axis crossing a longitudinal direction of said process cartridge. 10. A process cartridge according to claim 8, wherein said receiving-side shutter portion is disposed on an upper surface of said process cartridge in a state that said process cartridge is mounted to the main assembly of the apparatus and includes a rotatable member rotatable about a horizontal axis crossing a longitudinal direction of said process cartridge, said rotatable member being provided with an opening which opens in a radial direction of rotation of said rotatable member, and wherein said developer receiving opening is opened by said opening of said rotatable member being moved to oppose said developer receiving opening, and said developer receiving opening is closed by a portion of said rotatable member other than said opening being moved to oppose said developer receiving opening. 11. A process cartridge according to claim 8, wherein said receiving-side movable portion is rotatable, wherein said first receiving-side operating portion includes a projection having a portion extending along a rotational movement direction of said receiving-side movable portion, and said projection receives a force by engagement with said engageable member to rotate said receiving-side shutter portion, and wherein said second receiving-side operating portion includes a projection having a portion extending along the rotational moving direction of said receiving-side movable portion, said projection of said second receiving-side operating portion being engageable with a projection of a supplying-side operating portion of the supplying-side movable portion to apply a rotating force, thus rotating the supplying-side shutter portion. 12. A process cartridge according to claim 8, wherein said receiving-side shutter portion comprises a shutter member having an opening, a connecting member, and a recess in said connecting member, wherein said receiving-side movable portion comprises a rotatable member and a projection extending from said rotatable member, and wherein said projection is press-fitted into said recess so that movement of said receiving-side movable portion moves said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position. 13. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said process cartridge is capable of receiving a supply of a developer from a developer supply cartridge, wherein the developer supply cartridge includes a supplying-side developer accommodating portion for accommodating the developer, a supplying-side shutter portion movable between a developer-supply-permitting position for opening a developer supply opening for supplying the developer from the supplying-side developer accommodating portion into the process cartridge and a developer-supply-preventing position for closing the developer supply opening, a supplying-side movable portion movable to interrelatedly move the supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position, and an engageable member, said process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with the developer; a receiving-side developer accommodating portion for accommodating the developer; a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion; a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening; a regulating member; and a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-permitting position, wherein when said process cartridge is removed from the main assembly of the apparatus in a state that the developer supply cartridge is set in the main assembly of the apparatus, a) said receiving-side operating portion moves the supplying-side movable portion by engaging the supplying-side movable portion while the movement of said receiving-side movable portion is regulated by said regulating member so that receiving-side movable portion is maintained at the operating position, thereby interrelatedly moving the supplying-side shutter portion to the developer-supply-preventing position, and b) then said regulating member contacts the engageable member to release said receiving-side movable portion from said regulating member, thus permitting movement of said receiving-side movable portion, and said receiving-side movable portion moves said receiving-side shutter portion to the developer-reception-preventing position in interrelation with said receiving-side operating portion being moved by contacting the engageable member. 14. A process cartridge according to claim 13, wherein said receiving-side movable portion is rotatable, wherein said receiving-side operating portion includes a projection having a portion extending along a rotational moving direction of said receiving-side movable portion, and a supplying-side operating portion of the supplying-side movable portion includes a projection having a portion extending along a rotational moving direction of the supplying-side movable portion, and wherein the supplying-side shutter portion is rotated by said projection of said receiving-side movable portion engaging the projection of the supplying-side movable portion and applying a rotating force. 15. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion movable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of the receiving-side movable portion when the receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; and a supplying-side movable portion movable, when said developer supply cartridge is dismounted from the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, to interrelatedly move said supplying-side shutter portion from the developer-supply-permitting position to the developer-supply-preventing position by engaging the receiving-side operating portion of the receiving-side movable portion, when the receiving-side operating portion is positioned at the operating position and the movement of the receiving-side operating portion is regulated by the regulating member. 16. A developer supply cartridge according to claim 15, further comprising an engageable member fixed at a position upstream of said supplying-side movable portion with respect to a removing direction in which said developer supply cartridge is removed from the main assembly of the apparatus, wherein when said developer supply cartridge is removed from the main assembly of the apparatus, said engageable member releases, after said supplying-side shutter portion closes said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the regulating member regulates rotation of the receiving-side movable portion and the receiving-side shutter portion is placed at the developer-reception-permitting position to move the regulating member, thus permitting movement of the receiving-side movable portion and then said engageable member engages the receiving-side operating portion of the receiving-side movable portion to rotate the receiving-side movable portion, thus moving said receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position. 17. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion movable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a first receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of the receiving-side movable portion when the first or second receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; and an engageable member for moving the receiving-side shutter portion to the developer-reception-permitting position by contacting, when the process cartridge enters the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus, the regulating member when the first receiving-side operating portion is at the operating position to release the receiving-side movable portion from the regulating member, thus permitting movement of the receiving-side movable portion and then contacting the first receiving-side operating portion to move the receiving-side movable portion and to interrelatedly to move the receiving-side shutter portion to the developer-reception-permitting position; and a supplying-side movable portion movable to interrelatedly move said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position by engaging the second receiving-side operating portion of the receiving-side movable portion when the second receiving-side operating portion is at the operating position and the movement of the second receiving-side operating portion and the receiving-side movable portion is regulated by the regulating member, after said engageable member moves the receiving-side shutter portion to the developer-reception-permitting position. 18. A developer supply cartridge according to claim 17, wherein said engageable member is fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus. 19. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion movable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of the receiving-side movable portion when the receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; and a supplying-side movable portion movable to interrelatedly move said supplying-side shutter portion from the developer-supply-permitting position to the developer-supply-preventing position by engaging, when the process cartridge is removed from the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus with the receiving-side shutter portion placed at the developer-reception-permitting position, the receiving-side operating portion of the receiving-side movable portion when the movement of the receiving-side operating portion and the receiving-side movable portion is regulated by the regulating member. 20. A developer supply cartridge according to claim 19, further comprising an engageable member fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus, wherein when the process cartridge is removed from the main assembly of the apparatus, a) said engageable member releases, after said supplying-side shutter portion closes said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the regulating member regulates movements movement of the receiving-side movable portion and the receiving-side shutter portion is placed at the developer-reception-permitting position to move the regulating member, thus permitting movement of said receiving-side movable portion, and b) then said engageable member engages the receiving-side operating portion to rotate the receiving-side movable portion to move the receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position. 21. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a first receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when the receiving-side shutter portion is at the developer-reception-permitting position, a regulating member for regulating rotation of the receiving-side movable portion when the first or second receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; an engageable member fixed at a position downstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus; and a supplying-side movable portion for moving said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position and from the developer-supply-permitting position to the developer-supply-preventing position, wherein when said developer supply cartridge enters the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, a) said engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the first receiving-side operating portion is placed at the operating position to move the regulating member downwardly against an elastic force, thus permitting movement of the receiving-side movable portion, and b) then said engageable member engages the first receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly moves the receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said developer supply cartridge is removed from the main assembly of the apparatus in the state that the process cartridge is set in the main assembly of the apparatus, a) said engageable member releases, after said supplying-side shutter portion closes said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the second receiving-side operating portion is placed at the operating position to move the regulating member downwardly against the elastic force, thus permitting movement of the receiving-side movable portion, and b) then said engageable member engages the second receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly moves the receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position, wherein when said developer supply cartridge enters the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, after the receiving-side shutter portion opens the developer receiving opening, by engaging the receiving-side movable portion when the second receiving-side operating portion is placed at the operating position and the movement of the receiving-side movable portion is regulated by the regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-preventing position to the developer-supply-permitting position, and wherein said developer supply cartridge is removed from the main assembly of the apparatus in the state that the process cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, prior to the receiving-side shutter portion closing the developer receiving opening, by engaging the receiving-side movable portion when the second receiving-side operating portion is placed at the operating position and the movement of the receiving-side movable portion is regulated by the regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to the developer-supply-preventing position. 22. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a first receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating rotation of the receiving-side movable portion when the first or second receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; a first engageable member fixed at a position upstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus; a second engageable member fixed at a position downstream of said developer supply opening with respect to the entering direction; and a supplying-side movable portion for rotating said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position, wherein when the process cartridge enters the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus, a) said first engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the first receiving-side operating portion is placed at the operating position to move the regulating member downwardly against an elastic force, thus permitting movement of the receiving-side movable portion, and then b) said first engageable member engages the first receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly rotates the receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said developer supply cartridge enters the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, a) said second engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the first receiving-side operating portion is placed at the operating position to move the regulating member downwardly against an elastic force, thus permitting movement of the receiving-side movable portion, and then b) said second engageable member engages the first receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly rotates the receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when the process cartridge enters the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, after said first engageable member causes the receiving-side shutter portion to open the developer receiving opening, by engaging the receiving-side movable portion when the second receiving-side operating portion is laced at the operating position and the movement of the receiving-side movable portion is regulated by the regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is rotated from the developer-supply-preventing position to the developer-supply-permitting position, and wherein when said developer supply cartridge enters the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, after said second engageable member causes the receiving-side shutter portion to open the developer receiving opening, by engaging the receiving-side movable portion when the second receiving-side operating portion is placed at the operating position and the movement of the receiving-side movable portion is regulated by the regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is rotated from the developer-supply-preventing position to the developer-supply-permitting position. 23. A developer supply cartridge for supplying a developer into a process cartridge, said developer supply cartridge being detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the process cartridge includes an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, a receiving-side shutter portion movable between a developer-reception-permitting position for opening a developer receiving opening for receiving the developer to be used by the developing roller for a developing operation and a developer-reception-preventing position for closing the developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move the receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, the receiving-side movable portion including a first receiving-side operating portion which takes an operating position when the receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when the receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating rotation of the receiving-side movable portion when the first or second receiving-side operating portion is at the operating position, said developer supply cartridge comprising: a supplying-side developer accommodating portion for accommodating the developer; a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into the process cartridge through the developer receiving opening; a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening; a first engageable member fixed at a position upstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters the main assembly of the apparatus; a second engageable member fixed at a position downstream of said developer supply opening with respect to the entering direction; and a supplying-side movable portion for rotating said supplying-side shutter portion from the developer-supply-permitting position to the developer-supply-preventing position, wherein when the process cartridge is removed from the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus, a) said first engageable member releases, after said supplying-side shutter portion closes said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the second receiving-side operating portion is placed at the operating position to move the regulating member downwardly against an elastic force, thus permitting movement of the receiving-side movable portion, and b) then said first engageable member engages the second receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly rotate the receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position, wherein when said developer supply cartridge is removed from the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, a) said second engageable member releases, after said supplying-side shutter portion closes said developer supply opening, the receiving-side movable portion from the regulating member by contacting the regulating member when the second receiving-side operating portion is placed at the operating position to move the regulating member downwardly against an elastic force, thus permitting movement of the receiving-side movable portion, and b) then said second engageable member engages the second receiving-side operating portion to rotate the receiving-side movable portion, which interrelatedly rotates the receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position, wherein when the process cartridge is removed from the main assembly of the apparatus in a state that said developer supply cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, prior to said first engageable member causing the receiving-side shutter portion to close the developer receiving opening, by engaging the receiving-side movable portion when the movement of the receiving-side movable portion is regulated by the regulating member and the second receiving-side operating portion is placed at the operating position, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to the developer-supply-preventing position, and wherein when said developer supply cartridge is removed from the main assembly of the apparatus in a state that the process cartridge is set in the main assembly of the apparatus, said supplying-side movable portion is rotated, prior to said second engageable member causing the receiving-side shutter portion to close the developer receiving opening, by engaging the receiving-side movable portion when the movement of the receiving-side movable portion is regulated by the regulating member and the second receiving-side operating portion is placed at the operating position, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to the developer-supply-preventing position. 24. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a developer supply cartridge detachably mountable to said main assembly, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into a process cartridge, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, a supplying-side movable portion movable to interrelatedly move said supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position, and an engageable member; and (iii) the process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a regulating member, and a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a first receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-preventing position and a second receiving-side operating portion which takes the operating position when said receiving-side shutter portion is at the developer-reception-permitting position, wherein said developer supply cartridge and said process cartridge are mountable to said main assembly independently from each other, and wherein when said process cartridge enters said main assembly in a state that said developer supply cartridge is set in said main assembly, said regulating member regulates movement of said receiving-side movable portion, and said regulating member maintains said first receiving-side operating portion at the operating position, a) said regulating member contacts said engageable member to release said receiving-side movable portion from said regulating member, thus permitting movement of said receiving-side movable portion, b) then said receiving-side movable portion moves said receiving-side shutter portion to the developer-reception-permitting position in interrelation with said first receiving-side operating portion being moved by contacting said engageable member, and c) then said regulating member again regulates movement of said receiving-side movable portion and maintains the second receiving-side operating portion at the operating position and said receiving-side movable portion moves said supplying-side shutter portion to the developer-supply-permitting position by engagement of said supplying-side movable portion with said second receiving-side operating portion that is maintained at the operating position by said regulating member. 25. An apparatus according to claim 24, wherein said receiving-side movable portion is disposed on an upper surface of said process cartridge in a state that said process cartridge is mounted to said main assembly, and is rotatable about a horizontal axis crossing a longitudinal direction of said process cartridge. 26. An apparatus according to claim 24, wherein said receiving-side shutter portion is disposed on an upper surface of said process cartridge in a state that said process cartridge is mounted to said main assembly and includes a rotatable member rotatable about a horizontal axis crossing a longitudinal direction of said process cartridge, said rotatable member being provided with an opening which opens in a radial direction of rotation of said rotatable member, and wherein said developer receiving opening is opened by said opening of said rotatable member being moved to oppose said developer receiving opening, and said developer receiving opening is closed by a portion of said rotatable member other than said opening being moved to oppose said developer receiving opening. 27. An apparatus according to according to claim 24, wherein said receiving-side movable portion is rotatable, wherein said first receiving-side operating portion includes a projection having a portion extending along a rotational movement direction of said receiving-side movable portion, and said projection receives a force by engagement with said engageable member to rotate said receiving-side shutter portion, and wherein said second receiving-side operating portion includes a projection having a portion extending along the rotational moving direction of said receiving-side movable portion, said projection of said second receiving-side operating portion being engageable with a projection of a supplying-side operating portion of said supplying-side movable portion to apply a rotating force, thus rotating said supplying-side shutter portion. 28. An apparatus according to according to claim 24, wherein said receiving-side movable portion is rotatable, wherein said second receiving-side operating portion includes a projection having a portion extending along a rotational moving direction of said receiving-side movable portion, and a supplying-side operating portion of said supplying-side movable portion includes a projection having a portion extending along a rotational moving direction of said supplying-side movable portion, and wherein said supplying-side shutter portion is rotated by said projection of said second receiving-side operating portion engaging said projection of said supplying-side movable portion and applying a rotating force. 29. An apparatus according to according to claim 24, wherein said engageable member of said developer supply cartridge is fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters said main assembly, and wherein when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly, a) said downstream engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said receiving-side shutter portion is placed at the developer-reception-preventing position to move said regulating member, thus permitting movement of said receiving-side movable portion, and b) then said downstream engageable member engages said first receiving-side operating portion to rotate said receiving-side movable portion, thus moving said receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position. 30. An apparatus according to according to claim 24, wherein said supplying-side movable portion is disposed on a lower surface of said developer supply cartridge in a state that said developer supply cartridge is mounted to said main assembly, and is rotatable about a horizontal axis crossing a longitudinal direction of said developer supply cartridge. 31. An apparatus according to according to claim 24, wherein said supplying-side shutter portion is disposed on a lower surface of said developer supply cartridge in a state that said developer supply cartridge is set in said main assembly and includes a rotatable member rotatable about a horizontal axis crossing a longitudinal direction of said developer supply cartridge, said rotatable member being provided with an opening which opens in a radial direction of rotation of said rotatable member, and wherein said developer supply opening is opened by said opening of said rotatable member being moved to oppose said developer supply opening, and said developer supply opening is closed by a portion of said rotatable member other than said opening being moved to oppose said developer supply opening. 32. An apparatus according to according to claim 24, wherein said developer supply cartridge further includes a portion to be guided having a side surface to be regulated, an upper surface to be regulated, and a lower surface to be regulated, wherein when said developer supply cartridge enters said main assembly, said side surface to be regulated, said upper surface to be regulated and said lower surface to be regulated are regulated by a main assembly guide provided in said main assembly, and wherein in a state that said supplying-side movable portion is moving in engagement with said receiving-side movable portion, an upward movement of said upper surface to be regulated is prevented by said main assembly guide. 33. An apparatus according to according to claim 24, wherein said engageable member is fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters said main assembly. 34. An electrophotographic image forming apparatus according to claim 24, wherein said receiving-side shutter portion and said supplying-side shutter portion each comprise a shutter member having an opening, a connecting member, and a recess in said connecting member, wherein said receiving-side movable portion and said supplying-side movable portion each comprise a rotatable member and a projection extending from said rotatable member, wherein said projection of said receiving-side movable portion is press-fitted into said recess of said receiving-side shutter portion so that movement of said receiving-side movable portion moves said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, wherein said projection of said supplying-side movable portion is press-fitted into said recess of said supplying-side shutter portion so that movement of said supplying-side movable portion moves said supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position. 35. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a developer supply cartridge detachably mountable to said main assembly, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into a process cartridge, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, a supplying-side movable portion movable to interrelatedly move said supplying-side shutter portion between the developer-supply-permitting position and the developer-supply-preventing position, and an engageable member; and (iii) the process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a regulating member, and a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-permitting position, wherein said developer supply cartridge and said process cartridge are mountable to said main assembly independently from each other, and wherein when said process cartridge is removed from said main assembly in a state that said developer supply cartridge is set in said main assembly, a) said regulating member regulates movement of said receiving-side operating portion and maintains said receiving-side operating portion at the operating position, and said receiving-side movable portion moves said supplying-side movable portion by the engagement of said receiving-side operating portion at the operating position with said supplying-side movable portion, thereby interrelatedly moving said supplying-side shutter portion to the developer-supply-preventing position, and b) then said regulating member contacts said engageable member to release said receiving-side movable portion from said regulating member, thus permitting movement of said receiving-side movable portion, and said receiving-side movable portion moves said receiving-side shutter portion to the developer-reception-preventing position in interrelation with said receiving-side operating portion being moved by contacting said engageable member. 36. An apparatus according to according to claim 35, wherein said engageable member of said developer supply cartridge is fixed at a position upstream of said supplying-side movable portion with respect to a removing direction in which said developer supply cartridge is removed from said main assembly, and wherein when said developer supply cartridge is removed from said main assembly in a state that said process cartridge is set in said main assembly, said upstream engageable member releases, after said supplying-side shutter portion closes said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said receiving-side shutter portion is placed at the developer-reception-permitting position to move said regulating member, thus permitting movement of said receiving-side movable portion, and then said upstream engageable member engages said receiving-side operating portion to rotate said receiving-side movable portion, thus moving said receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position. 37. An apparatus according to according to claim 35, wherein said supplying-side movable portion is rotatable, and a supplying-side operating portion of said supplying-side movable portion includes a projection having a portion extending along a rotational movement direction of said supplying-side movable portion, and wherein said receiving-side movable portion is rotatable, and said receiving-side operating portion includes a projection having a portion extending along the rotational moving direction of said receiving-side movable portion, said projection of said supplying-side movable portion being engageable with said projection of said receiving-side operating portion to receive a rotating force, thus rotating said supplying-side shutter portion. 38. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with the developer, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of said receiving-side movable portion when said receiving-side operating portion is at the operating position; and (iii) a developer supply cartridge detachably mountable to said main assembly independently from said process cartridge, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into said process cartridge through said developer receiving opening, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, and a supplying-side movable portion movable, when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly, to interrelatedly move said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position by engagement with said receiving-side operating portion of said receiving-side movable portion in a state that said receiving-side operating portion is maintained at the operating position by said regulating member. 39. An apparatus according to according to claim 38, wherein said developer supply cartridge further includes an engageable member fixed at a position downstream of said supplying-side movable portion with respect to an entering direction in which said developer supply cartridge enters said main assembly, and wherein when said process cartridge is removed from said main assembly, a) said engageable member releases, after said supplying-side shutter portion closes said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said receiving-side shutter portion is placed at the developer-reception-permitting position to move said regulating member, thus permitting movement of said receiving-side movable portion, and b) then said engageable member engages said receiving-side operating portion to rotate said receiving-side movable portion to move said receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position. 40. An electrophotographic image forming comprising: (i) a main assembly; (ii) a process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with the developer, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a receiving-side movable portion movable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating movement of said receiving-side movable portion when said receiving-side operating portion is at the operating position; and (iii) a developer supply cartridge detachably mountable to said main assembly independently from said process cartridge, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into said process cartridge through said developer receiving opening, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, and a supplying-side movable portion movable, when said developer supply cartridge is dismounted from said main assembly in a state that said process cartridge is set in said main assembly, to interrelatedly move said supplying-side shutter portion from the developer-supply-permitting position to the developer-supply-preventing position by engagement with said receiving-side operating portion of said receiving-side movable portion in a state that said receiving-side operating portion is maintained at the operating position by said regulating member. 41. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a first receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when said receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating rotation of said receiving-side movable portion when said first or second receiving-side operating portion is at the operating position; and (iii) a developer supply cartridge detachably mountable to said main assembly, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into said process cartridge through said developer receiving opening, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, an engageable member fixed at a position downstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters said main assembly, and a supplying-side movable portion for moving said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position and from the developer-supply-permitting position to the developer-supply-preventing position, wherein said developer supply cartridge and said process cartridge are mountable to said main assembly independently from each other, wherein when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly, a) said engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said first receiving-side operating portion is placed at the operating position to move said regulating member downwardly against an elastic force, thus permitting movement of said receiving-side movable portion, and b) then said engageable member engages with said first receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly moves said receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said developer supply cartridge is removed from said main assembly in the state that said process cartridge is set in said main assembly, a) said engageable member releases, after said supplying-side shutter portion closes said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said second receiving-side operating portion is placed at the operating position to move said regulating member downwardly against the elastic force, thus permitting movement of said receiving-side movable portion, and b) then said engageable member engages said second receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly moves said receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position, wherein when said developer supply cartridge enters said main assembly in the state that said process cartridge is set in said main assembly, said supplying-side movable portion is rotated, after said receiving-side shutter portion opens said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-preventing position to the developer-supply-permitting position, and wherein when said developer supply cartridge is removed from said main assembly in the state that said process cartridge is set in said main assembly, said supplying-side movable portion is rotated, prior to said receiving-side shutter portion closing said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to developer-supply-preventing position. 42. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a first receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when said receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating rotation of said receiving-side movable portion when said first or second receiving-side operating portion is at the operating position; and (iii) a developer supply cartridge detachably mountable to said main assembly, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into said process cartridge through said developer receiving opening, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, a first engageable member fixed at a position upstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters said main assembly, a second engageable member fixed at a position downstream of said developer supply opening with respect to the entering direction, and a supplying-side movable portion for rotating said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position, wherein said developer supply cartridge and said process cartridge are mountable to said main assembly independently from each other, wherein when said process cartridge enters said main assembly in a state that said developer supply cartridge is set in said main assembly, a) said first engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said first receiving-side operating portion is placed at the operating position to move said regulating member downwardly against an elastic force, thus permitting movement of said receiving-side movable portion, and b) then said first engageable member engages said first receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly rotates said receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly, a) said second engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said first receiving-side operating portion placed at the operating position to move said regulating member downwardly against the elastic force, thus permitting movement of said receiving-side movable portion, and b) then said second engageable member engages said first receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly rotates said receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said process cartridge enters said main assembly in the state that said developer supply cartridge is set in said main assembly, a) said supplying-side movable portion is rotated, after said first engageable member causes said receiving-side shutter portion to open said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and b) in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is rotated from the developer-supply-preventing position to the developer-supply-permitting position, and wherein when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly a) said supplying-side movable portion is rotated, after said second engageable member causes said receiving-side shutter portion to open said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and b) in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is rotated from the developer-supply-preventing position to the developer-supply-permitting position. 43. An electrophotographic image forming apparatus comprising: (i) a main assembly; (ii) a process cartridge detachably mountable to said main assembly, said process cartridge including: an electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum, a receiving-side developer accommodating portion for accommodating the developer, a developer receiving opening for receiving the developer into said receiving-side developer accommodating portion, a receiving-side shutter portion movable between a developer-reception-permitting position for opening said developer receiving opening and a developer-reception-preventing position for closing said developer receiving opening, a receiving-side movable portion rotatable to interrelatedly move said receiving-side shutter portion between the developer-reception-permitting position and the developer-reception-preventing position, said receiving-side movable portion including a first receiving-side operating portion which takes an operating position when said receiving-side shutter portion is at the developer-reception-preventing position, and a second receiving-side operating portion which takes the operating position when said receiving-side shutter portion is at the developer-reception-permitting position, and a regulating member for regulating rotation of said receiving-side movable portion when said first or second receiving-side operating portion is at the operating position; and (ii) a developer supply cartridge detachably mountable to said main assembly, said developer supply cartridge including: a supplying-side developer accommodating portion for accommodating the developer, a developer supply opening for supplying the developer from said supplying-side developer accommodating portion into said process cartridge through said developer receiving opening, a supplying-side shutter portion movable between a developer-supply-permitting position for opening said developer supply opening and a developer-supply-preventing position for closing said developer supply opening, a first engageable member fixed at a position upstream of said developer supply opening with respect to an entering direction in which said developer supply cartridge enters said main assembly, a second engageable member fixed at a position downstream of said developer supply opening with respect to the entering direction, and a supplying-side movable portion for rotating said supplying-side shutter portion from the developer-supply-preventing position to the developer-supply-permitting position, wherein said developer supply cartridge and said process cartridge are mountable to said main assembly independently from each other, wherein when said process cartridge enters said main assembly in a state that said developer supply cartridge is set in said main assembly, a) said first engageable member releases, prior to said supplying-side shutter portion opening said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said first receiving-side operating portion is placed at the operating position to move said regulating member downwardly against an elastic force, thus permitting movement of said receiving-side movable portion, and b) then said first engageable member engages said second receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly rotates said receiving-side shutter portion from the developer-reception-preventing position to the developer-reception-permitting position, wherein when said developer supply cartridge enters said main assembly in a state that said process cartridge is set in said main assembly, a) said second engageable member releases, after said supplying-side shutter portion closes said developer supply opening, said receiving-side movable portion from said regulating member by contacting said regulating member when said second receiving-side operating portion is placed at the operating position to move said regulating member downwardly against the elastic force, thus permitting movement of said receiving-side movable portion, and b) then said second engageable member engages said second receiving-side operating portion to rotate said receiving-side movable portion, which interrelatedly rotates said receiving-side shutter portion from the developer-reception-permitting position to the developer-reception-preventing position, wherein when said process cartridge is removed from said main assembly in the state that said developer supply cartridge is set in said main assembly, said supplying-side movable portion is rotated, prior to said first engageable member causing said receiving-side shutter portion to close said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to the developer-supply-preventing position, and wherein when said developer supply cartridge is removed from said main assembly in the state that said process cartridge is set in said main assembly, said supplying-side movable portion is rotated, prior to said second engageable member causing said receiving-side shutter portion to close said developer receiving opening, by engaging said receiving-side movable portion when said second receiving-side operating portion is placed at the operating position and the movement of said receiving-side movable portion is regulated by said regulating member, and in interrelation with rotation of said supplying-side movable portion, said supplying-side shutter portion is moved from the developer-supply-permitting position to the developer-supply-preventing position.