In 1990 he was elected to the House of Representatives as representative for the Fourth District of Tokyo under the Liberal Democratic Party (LDP) ticket. He was appointed Parliamentary Vice-Minister of International Trade and Industry in 1996. Under Junichiro Koizumi's first Cabinet in 2001, he became Minister of State for Administrative and Regulatory Reform. He served as Minister of Land, Infrastructure and Transport from 2003 to 2004, and is currently chairman of the Highways Committee of the LDP Policy Affairs Research Council.
Following Prime Minister Yasuo Fukuda's resignation, Ishihara stood as a candidate for the LDP presidency. In the leadership election, held on September 22, 2008, Taro Aso won with 351 of the 527 votes; Ishihara placed fourth with 37 votes.1