Abstract: Kant's theory of the self mainly solves the problem of how the knowledge of universal necessity is possible and why the self exists. In current studies, most have separated these two aspects and failed to comprehend Kant's theory of the self completely. Even in the studies combining these two aspects, they either fail to recognize the possible contradictions or stand still in the face of contradictions. Borrowing the train of thought from Kant's transcendental aesthetic theory, these two aspects are completed through the transcendental deduction of self and the metaphysical deduction of self respectively. The former shows that the transcendental unity with spontaneous apperception is an important condition for the objective validity of knowledge, while the latter shows that the selfexists in the sense of Realit?t and not in the sense of Wirklichkeit. The distinction between Wirklichkeit and Realit?t is therefore the key to understanding Kant's theory of the self. It shows that Kant has no real contradiction in the question of the self.

Key words: Kant, Self Theory, Wirklichkeit, Realit?t