A belt driven mechanism which may be employed to transmit engine torque to an automotive electric rotary accessory such as an alternator. The belt driven mechanism is equipped with bearings disposed between a pulley around which a belt is wound and a torque output rotor. The belt driven mechanism also includes a coil spring mechanism having a length with a first and a second end portion to establish transmission of torque between the pulley and the rotor. Each of the first and second end portion has a plurality of points of attachment to a corresponding one of the pulley and the rotor, thereby distributing a mechanical load acting on the pulley or the rotor into fractions. This avoids local exertion of the load on the bearings, thereby prolonging the service life and ensuring the reliability of operation of the bearings.