This paper aims to analyze international factors that facilitated the participation of ethnic Koreans in Japan in the repatriation project to North Korea. Since the project is a complicated issue related to the international situation in the Cold War era, this study illuminates the overall aspect of the project, focusing on the perceptions and responses of major international actors such as North Korea, Japan, Korea, the International Committee of the Red Cross(ICRC), the United States, and the Soviet Union. The purpose of this study is to understand the background and process of the project, and to grasp how each country's policy decisions had an effect on the project. North Korea sought to secure labor and capital through the project, and to demonstrate the superiority of regime while Japan sought to solve domestic problems and improve relations with North Korea. South Korea tried to block the project, but there were limitations due to the international situation and domestic conditions. The ICRC emphasized the humanitarian nature of the project, but it was actually used for political purposes. The United States and the Soviet Union decided their positions on the project in consideration of their respective diplomatic interests, having an important impact on the progress of the project.