A clutch (3) includes: a clutch housing (32) which is provided with a drive plate (33) to be movable in an axial direction; a clutch hub (34) which transmits a rotary motive power to an output shaft; a clutch sleeve (35) which is provided with a driven plate (36) to be movable in the axial direction; and a pressure disk (40) which biases the drive plate (33) and the driven plate (36) toward the clutch hub (34), further includes a back torque limiter (7) which moves the pressure disk (40) in a direction away from the clutch hub (34) when back torque is applied, and the clutch hub (34) is provided with a restricting apparatus which restricts movement of the pressure disk (40) in the direction away from the clutch hub (34) when a number of rotations of the output shaft is less than a predetermined value.