What was the official name of the document Japan signed on USS Missouri in 1945?

The official name of the document Japan signed on USS Missouri was the Japanese Instrument of Surrender.

The instrument was the printed agreement that formalized Japan's capitulation to the Allied powers. It was signed in Tokyo Bay on September 2, 1945, by representatives of Japan and nine Allied nations.

Foreign Minister Mamoru Shigemitsu signed for the Japanese government, and General Yoshijiro Umezu signed for the Japanese armed forces. General Douglas MacArthur signed for the Allied powers, followed by representatives of the United States and the other participating nations.

The document required Japan to accept the provisions of the Potsdam Declaration and to order all Japanese forces to cease hostilities. It is sometimes confused with the Potsdam Declaration, but the two documents had different functions: Potsdam stated the surrender terms, while the instrument recorded Japan's formal acceptance.