Rikken Minseito

nihongo|Rikken Minseitō (Constitutional Democratic Party)|立憲民政党| Rikken Minseitō was one of the main political parties in pre-war Japan. It was also known as simply the ‘Minseitō’.

The Minseitō was founded on 1 June 1927, by the merger of the former Kenseikai with the Seiyu Honto, under the leadership of Hamaguchi Osachi. It viewed the Rikken Seiyukai as its main rival.

In the 1928 election, the Minseitō won 216 of the 464 seats in the lower house of Diet of Japan, thus becoming the single most important party. Hamaguchi became Prime Minister of Japan in 1929, and in the 1930 election, the party expanded its lead to 273 seats, thus obtaining an absolute majority. During its tenure, it advocated fiscal restraint, a conciliatory foreign policy, and ratified the London Naval Agreement of 1930. However, after Hamaguchi was assassinated by a right-wing fanatic in 1930, second party president Shidehara Kijuro was unable to maintain the party momentum.

Hamaguchi's successor, Prime Minister Wakatsuki Reijiro was unable to control the military or to prevent the Manchurian Incident, and his government collapsed in 1931.

The Minseitō lost its majority in Diet in the 1932 elections. It was able to recover its majority in the 1936 and 1937 elections only by adopting a more pro-military stance.

On 15 August 1940 the Minseitō voted to dissolve itself into the Imperial Rule Assistance Association as part of Fumimaro Konoe's efforts to create a single-party state, and thereafter ceased to exist.