Michel Decoust (born Paris, 19 November 1936) is a French composer and conductor. Decoust studied from 1956 to 1965 with Jean Rivier and Darius Milhaud at the Paris Conservatoire, as well as at the Cologne Courses for New Music in 1964–65, with Pierre Boulez and Karlheinz Stockhausen. He also studied orchestral conducting in 1965 with Boulez in Basle (). He has been awarded the Prix de Rome, the Ambron International Composition Prize, and a Besançon International Competition conducting prize.