Abstract: In order to promote the development of the commercialization of space activities and reform the present space management regime and free itself from the peace constitution and the satellite procurement agreement between Japan and the U.S., Japan adopted the Fundamental Act of Outer Space in May, 2008. The act allowed Japan the use of outer space for defensive military purpose. It also permitted the Japanese government to establish basic space measures to implement space exploration plan, establishing the Strategic Headquarters of Space Development. The act will have important impacts on the development of Japanese space activities, on peace and security in Asia and Pacific area, and on international space law.