On what date did Japan's surrender announcement reach the Japanese public by radio in 1945?

Japan's surrender announcement reached the Japanese public by radio on August 15, 1945.

Emperor Hirohito recorded the speech at the Imperial Palace in Tokyo, and it was broadcast at noon Japan Standard Time. The program became known as the Gyokuon-hōsō, or “Jewel Voice Broadcast.” It was the first time most Japanese people had heard their emperor speak.

The speech did not use the simple phrase “Japan surrenders.” Instead, Hirohito said that Japan had accepted the Allied declaration demanding surrender. The formal legal surrender took place later, on September 2, aboard USS Missouri in Tokyo Bay. This difference explains why August 15 and September 2 are both important dates in accounts of Japan's defeat.

The broadcast followed the atomic bombings of Hiroshima and Nagasaki and the Soviet Union's entry into the war against Japan. Its formal language and poor audio quality left some listeners unsure about what had happened, but the announcement marked the public end of Japan's wartime resistance.