The British Commonwealth Occupation Force (BCOF), was the name of the joint Australian, British, Indian and New Zealand military forces in occupied Japan from February 21, 1946 until the end of occupation in 1952. The force's primary objective was to enforce the terms of the unconditional surrender that had ended the war the previous September.

Up to 45,000 Australians served in BCOF, including an infantry contingent of 4,700, base units consisting of 5,300, an air force wing of 2,200 and 130 from the Australian General Hospital. The Australian Navy also had a presence in the region as part of the British Pacific Fleet. For two thirds of the period of occupation the Commonwealth was represented solely by Australians and throughout its existence BCOF was always commanded by an Australian officer.

The task of exercising military government over Japan was the responsibility of the United States forces. BCOF was required to maintain military control and to supervise the demilitarisation and disposal of the remnants of Japan's war making capacity. By the end of 1946 the task of demilitarising Japan was requiring less effort and the nature of BCOF's duties was changing. From this time guard duties and training began to occupy more of the occupying forces time. The force was dismantled during 1951 as responsibilities in Japan were handed over to the British Commonwealth Forces Korea.