Tōkyō 25th district is a constituency of the House of Representatives in the Diet of Japan. It is located in Western mainland Tokyo and covers, aside from the Izu and Ogasawara islands (part of the 3rd district), the most rural parts of the prefecture: the cities of Ōme, Fussa, Akiruno, Hamura and the Nishitama county. As of 2012, 321,319 eligible voters were registered in the district giving it the highest vote weight in Tokyo – several districts in former Tokyo city in Eastern Tokyo have more than 450,000 voters – but still more than 1.5 times as many voters as the least populated electoral districts in Japan.
Before the electoral reform of 1994, the area had been part of Tokyo 11th district that elected five Representatives by single non-transferable vote.
Since its creation, Tokyo 25th district has been a relatively safe seat for the Liberal Democratic Party and withstood the landslide Democratic victory in the 2009 general election. Its first representative, former defence minister Yōzō Ishikawa (Miyazawa→Kōno faction (present-day Asō faction)) who had represented the pre-reform 11th district since 1976, was succeeded by Shinji Inoue (Asō faction), a former MLIT bureaucrat.