Constitutional Democratic Party of Japan

The Constitutional Democratic Party of Japan (立憲民主党, Rikken-minshutō; CDP or CDPJ) is a liberal political party in Japan. It is the primary centre-left party in Japan, and was the second largest party in the National Diet behind the ruling Liberal Democratic Party (LDP).

It was founded in October 2017 as a split from the Democratic Party ahead of the 2017 general election, where it allied with the Japanese Communist Party and Social Democratic Party and overtook Kibō no Tō to become the largest opposition party. In late 2020, the party was re-founded following a merger with majorities of the Democratic Party For the People and the Social Democratic Party as well as some independent lawmakers. In the 2021 general election, it underperformed expectations and lost several seats. In the 2024 general election, the party surged and achieved the best result in its history, gaining 148 seats, up from 96 before. In 2026, it merged with Komeito in the House of Representatives to form the Centrist Reform Alliance in advance of the 2026 general election, however the party still caucuses as the CDP in the House of Councillors and in local elections. In the 2026 election, CDP-affiliated members of the CRA lost most of their seats, reducing the number of CDP-affiliated representatives from 144 to 21.

The party's platform supports raising the minimum wage, expanded welfare policies, the legalization of same-sex marriage, increased gender equality, renewable energy policies, decentralization, a multilateral and pragmatic foreign policy, the revision of the U.S.–Japan Status of Forces Agreement, tax reform and electoral reform. The party strongly opposes efforts to amend the Japanese Constitution to reinterpret Article 9 or codify the status of the Japan Self-Defense Forces and also opposes nuclear power.