On what date did the Japanese Instrument of Surrender take effect, formally ending World War II?

The Japanese Instrument of Surrender took effect on September 2, 1945, formally ending World War II.

The document was signed aboard the American battleship USS Missouri in Tokyo Bay shortly after 9:00 a.m. Japan Standard Time. It recorded Japan’s acceptance of the Allied surrender terms and was signed by Japanese representatives Mamoru Shigemitsu and General Yoshijiro Umezu.

Japan had announced its decision to surrender earlier, when Emperor Hirohito’s recorded broadcast was transmitted on August 15. However, that announcement did not replace the formal legal and military surrender ceremony. The instrument took effect at 9:25 a.m. local time after all required signatures were completed.

September 2 is therefore associated with the formal end of the Pacific War and is often called V-J Day. August 15 is also commemorated in several countries as the day Japan announced its surrender, making the two dates an occasional source of confusion.