This research describe about the efforts to normalize the bilateral relations between Japan-South Korea. This research uses the theory of the realist perspective. The level of analysis in this research is the state of the nation. This research also usses the theory of national interest and theoty of alliance. The method used in this research is a qualitative research, the data were collected through books, journals, articles, electronic media, mass media and websites on the internet. This research begins with and overview analysis of the conflict of relations between Japan and South Korea and how they normalize it. This research also explains how important the North Korea influences their relations, and also the United States as their balancing forces of North Korea and other threat source in East Asia. Japan and South Korea took steps to strengthen its military forces with the help of the United states, that makes some treaty between Japan and South Korea taken and makes their relations better.