Recently, as a serious of metal type-reproduction project progresses, lots of unknown facts were uncovered about metal-type, type casting and typesetting in the period of Koryo and Chosun Dynasty. Especially by discovering the oldest existing metal type so called Jeungdoga type(證道歌字) which was known by the author, not a few facts were turned over in relevant study. Nevertheless, some vague suppositions and existing opinions were carried by several scholars without scientific research and analysis or logical explanation. Some scholars continued to stand their ground in the traditional point of view to the category of the type-shape change. That is quite remote from reality and current theory. According to this study, height of metal-type was mostly kept in symmetrical within the typesetting rack, also bottom form of metal-type was like tunnel-shaped. Their bottom shape changed dependent on the method of typesetting from Koryo to late period of Chosun Dynasty. But the tunnel shaped bottom line was maintained from the second half of 15th century. The separated form of the upper and lower parts in casting method of type was consistantly used from an early period of metal-type printing in Korea, but adaptation later the ImJin type(壬辰字) in late period of 18th was not an acceptable fact in ease. Therefore we tried to straighten out the error and the wrong exiting theory in metal type printing, especially to the area of type-casting method, type shape so forth in Koryo and Chosun Dynasty.