On what date did Japan announce its surrender to the Allies in 1945?

Japan announced its surrender to the Allies on August 15, 1945.

Emperor Hirohito’s recorded radio address was broadcast at noon Japan Standard Time. It told the Japanese people that the government had accepted the terms of the Potsdam Declaration, although the emperor used formal language and did not plainly say the word “surrender” in the modern sense.

The broadcast followed the atomic bombings of Hiroshima and Nagasaki, the Soviet Union’s entry into the war against Japan, and intense debate within Japan’s leadership. Military hardliners even attempted a coup to prevent the recording from being broadcast, but the effort failed.

The formal legal surrender came later, on September 2, aboard USS Missouri. This is why August 15 is commonly called V-J Day in many countries, while the United States has also historically marked August 14 because of the time difference. The date refers to the announcement, not the signing ceremony.