The Potsdam Declaration stated the Allied surrender terms for Japan on July 26, 1945.
The declaration was issued during the Potsdam Conference by the United States, the United Kingdom, and China. It called for Japan's unconditional surrender and warned that refusing the terms would bring “prompt and utter destruction.” The Soviet Union did not sign the declaration at that time because it was still neutral in the war against Japan.
Japan initially did not accept the declaration. After the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and intense internal debate, the Japanese government decided to accept the terms. Hirohito's August 15 broadcast announced that decision to the public.
The Potsdam Declaration was therefore not the surrender document itself. It was the Allied statement of conditions that Japan agreed to accept. The formal written capitulation came later, on September 2, aboard USS Missouri in Tokyo Bay.