A clutch device (1A, 1B) comprising: an inner ring; an outer ring; a ratchet engagement mechanism including a notch provided on one of an outer peripheral portion of the inner ring and an inner peripheral portion of the outer ring, and an engaging member that is provided on the other of the outer peripheral portion of the inner ring and the inner peripheral portion of the outer ring and that engages with the notch to restrict a rotation between the inner ring and the outer ring in one direction; and a switching mechanism that includes a cam member (31, 41) movable in an axial direction with respect to the inner ring and the outer ring, and that switches an engagement state of the ratchet engagement mechanism between a first state where the engaging member is engaged with the notch and a second state where the engaging member is not engaged with the notch, by causing the cam member (31, 41) to move in the axial direction and come into contact with the engaging member, characterized in that when the engaging member is provided on the inner peripheral portion of the outer ring, the cam member (31, 41) includes a cam inner ring portion (32, 43) provided to rotate together with the inner ring, a cam outer ring portion (33, 42) disposed outside the cam inner ring portion (32, 43) in a radial direction, and a plurality of rolling elements disposed between the cam inner ring portion (32, 43) and the cam outer ring portion (33, 42), and the cam member (31, 41) moves in the axial direction to cause the cam outer ring portion (33, 42) to come into contact with the engaging member so as to switch the first state and the second state, and when the engaging member is provided on the outer peripheral portion of the inner ring, the cam member (31, 41) includes a cam outer ring portion (33, 42) provided to rotate together with the outer ring, a cam inner ring portion (32, 43) disposed inside the cam outer ring portion (33, 42) in the radial direction, and a plurality of rolling elements disposed between the cam inner ring portion and the cam outer ring portion (33, 42), and the cam member (31, 41) moves in the axial direction to cause the cam inner ring portion (32, 43) to come into contact with the engaging member so as to switch the first state and the second state. an inner ring; an outer ring; a ratchet engagement mechanism including a notch provided on one of an outer peripheral portion of the inner ring and an inner peripheral portion of the outer ring, and an engaging member that is provided on the other of the outer peripheral portion of the inner ring and the inner peripheral portion of the outer ring and that engages with the notch to restrict a rotation between the inner ring and the outer ring in one direction; and a switching mechanism that includes a cam member (31, 41) movable in an axial direction with respect to the inner ring and the outer ring, and that switches an engagement state of the ratchet engagement mechanism between a first state where the engaging member is engaged with the notch and a second state where the engaging member is not engaged with the notch, by causing the cam member (31, 41) to move in the axial direction and come into contact with the engaging member, characterized in that when the engaging member is provided on the inner peripheral portion of the outer ring, the cam member (31, 41) includes a cam inner ring portion (32, 43) provided to rotate together with the inner ring, a cam outer ring portion (33, 42) disposed outside the cam inner ring portion (32, 43) in a radial direction, and a plurality of rolling elements disposed between the cam inner ring portion (32, 43) and the cam outer ring portion (33, 42), and the cam member (31, 41) moves in the axial direction to cause the cam outer ring portion (33, 42) to come into contact with the engaging member so as to switch the first state and the second state, and when the engaging member is provided on the outer peripheral portion of the inner ring, the cam member (31, 41) includes a cam outer ring portion (33, 42) provided to rotate together with the outer ring, a cam inner ring portion (32, 43) disposed inside the cam outer ring portion (33, 42) in the radial direction, and a plurality of rolling elements disposed between the cam inner ring portion and the cam outer ring portion (33, 42), and the cam member (31, 41) moves in the axial direction to cause the cam inner ring portion (32, 43) to come into contact with the engaging member so as to switch the first state and the second state.