Japanese militarism was the ideology in the Empire of Japan which advocated the belief that militarism should dominate the political and social life of the nation, and the belief that the strength of the military is equal to the strength of a nation. It was most prominent from the start of conscription after the Meiji Restoration until the Japanese defeat in World War II, roughly 1873 to 1945. Since then, pacifism has been enshrined in the postwar Constitution of Japan as one of its key tenets.

The Empire of Japan, also referred to as the Japanese Empire, Imperial Japan, or simply Japan, was the Japanese nation-state that existed from the Meiji Restoration in 1868 until the enactment of the reformed Constitution of Japan in 1947. From 29 August 1910 to 2 September 1945, the Empire of Japan included the naichi and the gaichi. It also ruled colonies such as Kwantung, South Seas, Mantetsu, and its concessions. In the closing stages of World War II, with Japan defeated alongside the rest of the Axis, on 2 September 1945 the formalized Japanese Instrument of Surrender was issued in compliance with the Potsdam Declaration of the victorious Allies; and Japanese territory was immediately reduced to the Japanese archipelago as it is today.