Nine Allied governments signed Japan’s formal surrender document in 1945.
The nine Allied governments were the United States, China, the United Kingdom, the Soviet Union, Australia, Canada, France, the Netherlands, and New Zealand. Their representatives signed after General Douglas MacArthur accepted the surrender on behalf of the Allied powers.
The number nine refers to Allied governments, not to the total number of people who signed. Japan had two principal signatories, while the Allied side included MacArthur and representatives of the nine governments. This distinction explains why photographs show more signatories than the answer suggests.
The participating governments reflected the multinational nature of the Pacific War and the broader Allied coalition. Some representatives came from countries that had fought Japan directly in Asia and the Pacific, while others represented governments whose forces had contributed to the wider war against the Axis powers. The document therefore recorded Japan’s surrender to a coalition rather than to the United States alone.