| Kōji Matsui | |
| Office: | 27th Mayor of Kyoto |
| Term Start: | 25 February 2024 |
| Predecessor: | Daisaku Kadokawa |
| Office2: | Deputy Chief Cabinet Secretary |
| Term Start2: | 16 September 2009 |
| Term End2: | 8 June 2010 |
| Primeminister2: | Yukio Hatoyama |
| Predecessor2: | Katsuhito Asano |
| Successor2: | Tetsuro Fukuyama |
| Office3: | Member of the House of Councillors |
| Termstart3: | 2001 |
| Term End3: | 2013 |
| Constituency3: | Kyoto at-large district |
| Birth Date: | 25 April 1960 |
| Birth Place: | Kyoto, Japan |
| Education: | University of Tokyo |
| Party: | Independent |
| Otherparty: | Democratic Party of Japan |
| Website: | https://matsuikoji.kyoto/ |
is a Japanese politician who was elected Mayor of Kyoto in 2024. Matsui was a member of the House of Councillors from Kyoto at-large district between 2001 and 2013, as a member of the Democratic Party of Japan. He served as Deputy Chief Cabinet Secretary in the Yukio Hatoyama Cabinet.
Before entering politics Matsui was a bureaucrat in the Ministry of International Trade and Industry.
Koji Matsui was born in Kyoto on April 25, 1960. His family owned an inn in central Kyoto where they also lived. Matsui enrolled at the University of Tokyo, where he majored in international relations. While a student he read the novel The Summer of Bureaucrats (官僚たちの夏) by Saburo Shiroyama, which inspired him to join the Ministry of International Trade and Industry when he graduated in 1983.[1]
While in the ministry Matsui was sent to the Kellogg School of Management at Northwestern University in the United States for further education and earned an MBA in 1990. From 1994 to 1996 he was seconded to the Cabinet Secretariat. In 2000 he retired from the Ministry to enter politics.[2]
Matsui was elected from Kyoto at-large district as a member of the Democratic Party of Japan in the 2001 House of Councillors election. He was reelected in 2007.[3]
When the DPJ took power in the 2009 House of Representatives election, Matsui was appointed Deputy Chief Cabinet Secretary under Prime Minister Yukio Hatoyama. He left when Hatoyama was replaced by Naoto Kan in June 2010. Matsui declined to run for reelection in the 2013 House of Councillors election. He afterwards worked as a professor at Keio University.
In November 2023 Matsui announced he would run in the 2024 Kyoto mayoral election. He subsequently received the endorsements of the Liberal Democratic Party, the Constitutional Democratic Party of Japan, the Komeito and the Democratic Party for the People. He was also endorsed by outgoing Mayor Daisaku Kadokawa and the Governor of Kyoto Prefecture Takatoshi Nishiwaki. Matsui won the election when it was held in February 2024, beginning his term on February 25.[4]