One-way clutch unit and one-way clutch therefor

There is provided a compact one-way clutch unit that can perform connection and disconnection of power in two systems. An end portion on a side of a deep groove ball bearing portion 65 of a second one-way clutch 2 is disposed in an annular recess 67, which is provided at an end portion in an inner peripheral surface of a first inner ring 7, so that the dimension in an axial direction of a one-way clutch unit is reduced. Further, an outer peripheral diameter on a side of the deep groove ball bearing portion 65 is made smaller than that on the side of a one-way clutch portion 60 of a second outer ring 14 so as to reduce a diameter of the recess 67 and the outer peripheral diameter of the first outer ring 5 of the first one-way clutch 1.