The Japan Cooperative Party (Japanese: 日本協同党, Nihon Kyōdōtō) was a political party in Japan.

On 18 December 1945,^[1] the party was established by the center of the former Sangyō Kumiai (lit. 'Industrial Association') such as cooperatist Sengoku Kotaro [ja] and dairy farmer Kurosawa Torizo [ja].^[3][5] It initially had around 20 members,^[1] and journalist Yamamoto Sanehiko [ja] was assumed chairperson of the party.^[2][4][6] On 4 January 1946, the Supreme Commander for the Allied Powers (SCAP) published a memorandum pertaining to the Purge (from public office) based on the Potsdam Declaration and an order from the State-War-Navy Coordinating Committee (SWNCC).^[7] Only two of the party's 23 legislative members were able to escape the Purge.^[8] It won 14 seats in the April 1946 elections.^[9] On the other hand, the dominant Liberal Party could not win an absolute majority, so the Shidehara Cabinet did not resign and began maneuvering to cling to power.^[10] In response, the party supported a movement for the campaign to oust the cabinet advocated by the Socialist Party, and formed a four-party joint committee of the Japan Cooperative Party, the Socialist Party, the Liberal Party, and the Communist Party.^[11] The four-party joint committee started negotiations for a coalition government after defeating the cabinet, but the idea eventually failed due to disagreements within the subcommittee.^[12] In May, it merged with several smaller parties to form the Cooperative Democratic Club, later renamed the Cooperative Democratic Party.^[13]

After World War II, several new parties emerged in pursuit of co-operatism as a modification of capitalism, the Japan Cooperative Party was its origin.^[3] The party advocated cooperative socialism, co-operatism and Kōtō Goji (lit. 'defend and maintain of the imperial lineage') in its platform.^[2][3] In its policy outline, it described co-operatism as "stabilize the lives of the people through mutual aid between cities and farming / fishing villages centred on cooperatives, and establish and encourage a production system that integrates agriculture, manufacturing and commerce."^[3] In addition, it advocated defeat the monopoly capital and every feudalistic element, and aimed at centrism (i.e. stand between capitalism and socialism).^[2] The party's mainly base was urban manufacturers and merchants, landlords, wealthy peasants, and small- to medium-sized manufacturers and merchants.^[2][4]