A power transmission device has a pressure member (5) pressing drive-side clutch plates and driven-side clutch plates against each other or releasing a press-contact force. A clutch spring (10) urges the pressure member (5) in a direction so that the clutch plates are pressed against each other. A separate receiving member (11) is attached to the pressure member (5). A back-torque limiting cam reduces press-contact force between the clutch plates when the rotation speed of an output member exceeds the rotation speed of an input member. A rotation restricting portion (8a) restricting rotation, relative to the clutch member (4), of the pressure member (5) that has moved due to activation of the push rod (9). A clearance t is maintained between the pair of cam surfaces that constitute the back-torque limiting cam.