What was the official document called that Japan signed to end World War II in 1945?

The official document Japan signed to end World War II was the Japanese Instrument of Surrender.

The instrument was signed aboard the American battleship USS Missouri in Tokyo Bay on 2 September 1945. Japanese Foreign Minister Mamoru Shigemitsu signed for the Japanese government, while General Yoshijiro Umezu signed for Imperial General Headquarters. General Douglas MacArthur then accepted the surrender on behalf of the Allied powers.

The document required Japan to accept the provisions of the Potsdam Declaration, which demanded Japan’s unconditional surrender and limited Japanese sovereignty to the home islands and other territories designated by the Allies. It also ordered Japanese forces to cease hostilities and disarm.

The instrument is sometimes confused with the Potsdam Declaration. The declaration was an Allied demand issued before Japan surrendered; the instrument was the legal document signed after Japan accepted those terms. The signing ceremony lasted about 23 minutes and formally ended the Pacific War.