Toshio Hosokawa (細川 俊夫, Hosokawa Toshio, born 23 October 1955) is a Japanese composer of contemporary classical music. He studied in Germany but returned to Japan, finding a personal style inspired by classical Japanese music and culture. He has composed operas, the oratorio Voiceless Voice in Hiroshima, and instrumental music.
He was the cofounder and artistic director of a Japanese festival for contemporary music and has been a composer in residence at international festivals such as the Venice Biennale, Lucerne Festival, Warsaw Autumn and Rheingau Musik Festival. His operas premiered at the Munich Biennale and La Monnaie, among others.