Emperor Hirohito approved the decision for Japan to surrender in August 1945.
Japan’s cabinet was deeply divided over whether to accept the Allied terms after the atomic bombings and the Soviet entry into the war against Japan. At an imperial conference on August 9–10, the deadlock continued. Hirohito then supported acceptance of the Potsdam Declaration, helping break the tie among the decision-makers.
He later recorded an address explaining the surrender, which was broadcast to the Japanese public on August 15. The speech used formal imperial language, and many listeners had never heard the emperor’s voice before.
Hirohito’s role is often described as decisive, but the surrender resulted from several interacting pressures: military defeat, the atomic bombings of Hiroshima and Nagasaki, the Soviet offensive in Manchuria, and the possibility of further attacks on Japan. The formal instrument was signed aboard USS Missouri on September 2.