On what date did the Allied occupation of Japan officially end?

The Allied occupation of Japan officially ended on April 28, 1952.

The occupation ended when the Treaty of San Francisco entered into force, restoring Japan’s sovereignty after the postwar settlement. The treaty had been signed on September 8, 1951, but its legal effect began on April 28, 1952. The United States and many other Allied countries were parties to the treaty.

The date does not mean every foreign military presence immediately disappeared. A separate security treaty allowed American forces to remain stationed in Japan with the Japanese government’s consent. Okinawa and several other island groups also remained under U.S. administration for longer periods.

The occupation began in August 1945 and was directed by the Supreme Commander for the Allied Powers, General Douglas MacArthur. Its reforms included demilitarization, political restructuring, land reform, and the adoption of Japan’s postwar constitution, which came into effect in 1947.