Nine Allied countries supplied national representatives who signed Japan’s surrender instrument.
The signatories represented the United States, China, the United Kingdom, the Soviet Union, Australia, Canada, France, the Netherlands, and New Zealand. General Douglas MacArthur signed first as Supreme Commander for the Allied Powers, and Fleet Admiral Chester Nimitz signed for the United States before the other national representatives added their signatures.
The group reflected the major Allied governments involved in the Pacific War and the wider coalition against Japan. Their representatives signed on the deck of USS Missouri in Tokyo Bay on September 2, 1945. Japanese Foreign Minister Mamoru Shigemitsu and General Yoshijiro Umezu signed before the Allied delegations.
The number nine refers to the Allied national signatories, not the total number of people present at the ceremony. MacArthur’s separate signature as supreme commander is also why simple counts of signatures can be confusing. The ceremony was carefully arranged so that the surrender applied to Japan’s forces across the areas controlled by the Allied powers.