A power transmitting apparatus comprising: a clutch housing rotatable together with an input member; a plurality of driving clutch plates mounted on the clutch housing and rotatable together with the clutch housing; a plurality of driven clutch plates alternately arranged between the driving clutch plates and movable for carrying out the pressure--contact or release relative to the driving clutch plates; a clutch member (4, 4") of a substantially cylindrical configuration mounting thereon the driven clutch plates and connected to an output member; a pressure member (5, 5') moveable for carrying out the pressure-contact or release of the driving clutch plates relative to the driven clutch plates; pressure-contact assisting cam for increasing the pressure-contacting force between the driving clutch plates and driven clutch plates when a condition in which a rotational force inputted to the input member can be transmitted to the output member is achieved, and back-torque limiting cam for releasing the connection between the driving clutch plates and the driven clutch plates when the rotation speed of the output member has exceeded that of the input member characterized in; that at least one cam surface (11a, 11b or 13a, 13b) of the pressure-contact assisting cam or the back-torque limiting cam is arranged so as to extend along a circumferential edge of the clutch member (4, 4"), and that a crowning is formed on said at least one cam surface (11a, 11b or 13a, 13b) along its extending direction or its width direction, the extending direction being defined as a direction parallel to the rotational axis, the width direction being defined as a radial direction of the clutch member (4, 4"). a clutch housing rotatable together with an input member; a plurality of driving clutch plates mounted on the clutch housing and rotatable together with the clutch housing; a plurality of driven clutch plates alternately arranged between the driving clutch plates and movable for carrying out the pressure--contact or release relative to the driving clutch plates; a clutch member (4, 4") of a substantially cylindrical configuration mounting thereon the driven clutch plates and connected to an output member; a pressure member (5, 5') moveable for carrying out the pressure-contact or release of the driving clutch plates relative to the driven clutch plates; pressure-contact assisting cam for increasing the pressure-contacting force between the driving clutch plates and driven clutch plates when a condition in which a rotational force inputted to the input member can be transmitted to the output member is achieved, and back-torque limiting cam for releasing the connection between the driving clutch plates and the driven clutch plates when the rotation speed of the output member has exceeded that of the input member characterized in; that at least one cam surface (11a, 11b or 13a, 13b) of the pressure-contact assisting cam or the back-torque limiting cam is arranged so as to extend along a circumferential edge of the clutch member (4, 4"), and that a crowning is formed on said at least one cam surface (11a, 11b or 13a, 13b) along its extending direction or its width direction, the extending direction being defined as a direction parallel to the rotational axis, the width direction being defined as a radial direction of the clutch member (4, 4").