To provide a one-way clutch, hardly susceptible to a lubricant, and obtaining enough locking force even in various environments.

In the peripheral surface 1a of one raceway track member (a rotating shaft 1) opposite to the cam face 2a of the other raceway track member (an outer ring 2), a groove 1v for discharging a lubricant toward the end of one-way clutch with the relative rotation for locking one-way clutch is formed in an area sliding contact with a roller 5. By this constitution, lubricant on the raised part (the outer peripheral surface 1a of the rotating shaft 1) where the groove 1v is not formed is taken in the groove 1v and discharged along the groove 1v toward the end of the raceway track member. Accordingly, in the one-way clutch of the invention, the lubricant interposed between the roller 5 and the raceway track member is quickly removed.