The alliance of the Republic of Korea (ROK or South Korea) and the United States of America (or US) was brought as a result of the Korean War. To South Korea, the war was to defend freedom and democracy with democratic countries including US, on the other side, to North Korea, it was to spread the communism revolution by invading South Korea. The original alliance of both South Korea and US was military alliance. It was gradually extended to the fields of politics, economy, society and culture. The ROK-US alliance continues to change as a result of both advanced international status of South Korea and the status of the United States in international society. Especially both countries have shown about differences Japan and China, and North Korea. And the lingering awareness of the difference between the two sides in the alliance still faces the challenges to be solved. This paper suggests ways to promote future peace condition on the Korean peninsula. To do that, this paper tries to show the basic principles for the identity principle, the principle of universality, the principle of reciprocity.