This thesis deals with Song Du-Yul’s unification philosophy, which is a philosophical inquiry into the division and unification of the Korean Peninsula. His unification philosophy basically starts off from thoughts on the ‘border’ of ‘South and North’, and then onto producing ‘the third something’. He believes the mutual antagonism of ‘South or North’ is premised on the totality of the Korean Peninsula. Therefore, based on the totality of the Peninsula, he proposes an ‘epistemological transition’ to ‘South and North’, and defines unification as a process of producing a ‘common denominator’ as the third something from this epistemological transition. To his end, he proposes a ‘innate and critical approach’ and a ‘hermeneutic circle’ as methods to understand the dissimilarities of the ‘the other’ in and of themselves, from the perspective of ‘philosophy of a borderer’, and goes on to discussing ‘coexistence of dissimilarities’ and ‘change as a process’. Also, in relation to the ‘border experience’, he asserts ‘reflexive nationalism’ and ‘subjective globalization’ as a move beyond the conflict between the South’s ‘globalization’ and the North’s ‘uniformism’, through which he is able to bring out the universal significance of creating a unified Korean Peninsula. Based on such analysis, this thesis focuses on Song Du-Yul’s unification philosophy, assesses its significance and the limitations, and proposes a new unification philosophy, based on ‘the otherness of the other’, consisting of ‘philosophy of the two’, ‘asymmetrical communication’ and ‘creation of commonalities through inter-Korea communication’.