Pak Jigye is a Confucian scholar of Chosun dynasty in the 17th century. This article examines his theory of Insim-Dosim, and analyzes it from philosophical perspective. Although Pak considered himself as a devout follower of Zhuxi, his theory of Insim-Dosim was quite different from Zhuxi's. There are two fundamental propositions underlying Zhuxi's theory of Insim-dosim: (i) Insim and Dosim are not two minds; rather, they are two aspects of one single mind, and (ii) both Insim and Dosim are in the state of post-issued mind(Yibal). For Zhuxi, these two propositions are inextricably related to the concept of Jigak. However, he struggles between the ontological unity of Insim and Dosim and their axiological duality, and finally reaches an ambiguous conclusion on the issue. Pak Jigye takes a different path, insisting that both Insim and Dosim belong to every aspect of mind including Mibal and Yibal, and that they are two separate minds. His theory is based on solid dichotomy of Insim and Dosim, and it denies Zhuxi's premise on the unity of mind. According to him, Dosim and Insim are drastically different in terms of their forms, origins and the ways of occurrence. Their relation is analogous to the relation between sovereign and subject in the sense that the former supervises the latter while the latter follows the orders of the former. Therefore, Insim always comes under the control of Dosim even at its best, and cannot be reached at the level of Dosim. Pak maintains that Insim must be guided and domesticated by Dosim in order to reach its highest state. His theory is unique and differs from Zhuxi's. And it reveals diverse aspects of Neo-confucian thoughts in the 17th century Chosun, which have less discussed in the literature of Korean Neo-confucianism.