|Founded||June 22, 1898|
|Dissolved||September 13, 1910|
|Succeeded by||Rikken Kokumintō|
The Kenseitō was founded in June 1898, as a merger of the Shimpotō headed by Ōkuma Shigenobu and the Liberal Party of Japan (Jiyūtō) led by Itagaki Taisuke, with Ōkuma as party president. The merger gave the new party an overwhelming majority in the Lower House of the Diet of Japan. After the collapse of the Itō administration, Ōkuma became Prime Minister of Japan, despite concerns by Yamagata Aritomo and other members of the Meiji oligarchy and genrō that this would result in a dilution of their authority. One of Ōkuma's first acts as prime minister was to pass much-needed fiscal retrenchment legislation, trimming the number of bureaucrats on the government payroll. However, he was unable to curtail spending for the post-First Sino-Japanese War military expansion program he inherited from the Itō administration.
During the August 1898 general election, the Kenseitō won 260 out of 300 seats contested; however, the party soon collapsed. Members of the former Jiyūtō felt that Ōkuma did not distribute the cabinet seats in fair proportion to their party, and joined with Yamagata Aritomo and other conservative elements in the Diet to criticize Minister of Education Ozaki Yukio for a speech which they felt promoted republicanism. Following Ozaki’s resignation, the former Jiyūtō faction continued to attack the government until Ōkuma's cabinet disintegrated.
The former Jiyūtō faction reorganized itself into the 'New Kenseitō' in November 1898 with Itagaki as its president. The reformed party allied itself with the new government led by Yamagata, and pushed for land tax reform and expansion of suffrage. The ‘New Kenseitō” joined Itō Hirobumi’s Rikken Seiyūkai in 1900.
The remaining party members still loyal to Ōkuma reorganized themselves into the 'Kensei Hontō' (憲政本党 Original Kenseitō ) in November 1898. However, 34 party members defected in 1901 over Ōkuma’s support for the 4th Itō administration’s efforts to raise taxes to pay for expenses incurred in the Boxer Rebellion. In the 1903 general election, the Kensei Hontō won 85 seats, and joined forces with the Rikken Seiyūkai to oppose the first Katsura Tarō administration. In 1907, Ōkuma resigned as president, and in the 1908 General Election, the Kensei Hontō won only 70 seats in the Diet, as opposed to the Rikken Seiyūkai’s 187.
The Kensei Hontō merged with smaller parties to form the Rikken Kokumintō in March 1910.
- Banno, Junji, The Establishment of The Japanese Constitutional System. Routledge (1995) ISBN 0-415-13475-7
- Sims, Richard (1990). Japanese Political History Since the Meiji Renovation 1868-2000. University of California Press. ISBN 0-520-06838-6.
- Sims. Japanese Political History Since the Meiji Renovation. page 81