A one way clutch comprises an outer race including a radially outer first annular part to which rotation is input from outside and a radially inner second annular part capable of rotating when receiving rotation from the first annular part, an inner race provided radially inside the outer race and rotatable relative to the outer race, a plurality of torque transmission members provided between the outer race and the inner race to transmit torque between the outer race and the inner race, and a coupling mechanism that couples the first annular part and the second annular part together to make them integrally rotatable when the speed of rotation input from outside is lower than a specific speed and decouples them when the speed of rotation exceeds the specific speed.