Abstract: The present invention provides a one-way clutch of roller type comprising an outer race having at least one pocket provided at its inner periphery with a cam surface, an inner race spaced apart from the outer race radially inside of the outer race and coaxially arranged for a relative rotational movement, a roller disposed in the pocket and adapted to transmit torque between the outer race and the inner race when engaged by the cam surface, a cage having a cylindrical portion with a window for holding the roller and a flange portion extending outwardly from the cylindrical portion in the outer diameter direction and rotatable relative to the outer race, the window having a circumferential window width smaller than a diameter of the roller, and a spring disposed in the pocket and adapted to bias the roller toward an engagement direction with respect to the cam surface, and wherein an inclined surface portion inclined in the axial direction is provided on the inner periphery of the pocket.