Junichiro Koizumi (小泉 純一郎, Koizumi Jun'ichirō?, born January 8, 1942) is a Japanese politician who served as Prime Minister of Japan from 2001 to 2006. He is going to retire from politics when his term in parliament ends.

Widely seen as a maverick leader of the Liberal Democratic Party (LDP), he became known as an economic reformer, focusing on Japan's government debt and the privatization of its postal service. In 2005, Koizumi led the LDP to win one of the largest parliamentary majorities in modern Japanese history.

Koizumi also attracted international attention through his deployment of the Japan Self-Defense Forces to Iraq, the first foreign deployment of the Japanese military since World War II, and his visits to Yasukuni Shrine which led to diplomatic tensions with China and Korea.