Kamen Rider Fourze (仮面ライダーフォーゼ, Kamen Raidā Fōze) is a Japanese tokusatsu drama in Toei Company's Kamen Rider Series, being the thirteenth series in the Heisei period run and the twenty-second overall. It began airing on September 4, 2011, the week following the conclusion of Kamen Rider OOO, joining Kaizoku Sentai Gokaiger and then Tokumei Sentai Go-Busters in the Super Hero Time lineup.

The series commemorates not only the Kamen Rider Series' 40th anniversary but also the 50th anniversary of spaceflight, which began with Yuri Gagarin's flight in 1961. The show's catchphrase is "Switch on youth 'cause we're going into space!" (青春スイッチオンで宇宙キター！, Seishun suitchi on de uchū kitā!), referencing the Fourze Driver transformation belt which gets its various powers from devices called Astroswitches to conjure attachments to Fourze's limbs. As with the two previous series, the protagonist of Fourze made his debut in the annual summer film of the show's direct predecessor, appearing in Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals.