PURPOSE: To provide a one-way clutch having a less number of component items and attach the same with less manhours and to prevent the clutch from coming off.

CONSTITUTION: A cylindrical body of an outer ring shell 1 is formed at one end part with an L-like bent flange part 1b, and an axially protrusive part 1f extended toward the cylindrical body from the flange part, and a hole for receiving therein a rotary shaft 4a is formed in a wall surface of a housing 4, and a recess 4a is formed circumferentially of the hole. Further, the flange part 1b formed at the one end part of the cylindrical body of the outer ring shell 1 is locked in the inside of the wall surface of the housing 4, and the axially protrusive part 1f is located in the recess 4a.