2003 was the 15th year of Heisei in Japan.

Incumbents

• Emperor: Akihito
• Prime Minister: Junichiro Koizumi
• Chief Cabinet Secretary: Yasuo Fukuda
• Governor of Tokyo: Shintaro Ishihara

Events

Mori Tower, the centerpiece of Roppongi Hills, opened in April.

• March 19: Extension of the Eidan Hanzomon Line from Suitengumae to Oshiage becomes operational.
• March 31: Agriculture Minister Tadamori Oshima resigns due to a farm subsidy scandal; Koizumi replaces him with Yoshiyuki Kamei.
• April 1: The Postal Agency becomes Japan Post, a public corporation.
• April 1: Saitama becomes a city designated by government ordinance.
• April 25: Grand opening of Roppongi Hills.
• July 7: Noto Airport opens.
• July 26: Diet of Japan authorizes the deployment of Japanese troops to Iraq.
• August 10: Okinawa Monorail opens.
• September 20: Koizumi announces a new cabinet: Taro Aso becomes Minister of Internal Affairs, Shoichi Nakagawa becomes Minister of Economy, Trade and Industry, Sadakazu Tanigaki becomes Minister of Finance and Yuriko Koike becomes Minister of Environment.
• September 26: The Liberal Party merges into the Democratic Party of Japan.
• October 1: Shinagawa Station opens platforms for the T„kaid“ Shinkansen.
• October 10: House of Representatives is dissolved.
• November 9: In the Japan general election, 2003, the Democratic Party of Japan realizes a slight gain against the ruling Liberal Democratic Party.

Deaths

• January 12: Kenji Fukasaku, film director
• April 20: Daijiro Kato, motorcycle racer
• October 31: Kamato Hongo, oldest person in the world
• November 13: Mitoyo Kawate, oldest person in the world