A motor/generator is arranged radially outward of a middle portion of a front cover of a torque converter so that at least a part of the motor/generator axially overlaps the torque converter, with a predetermined gap (C) between the front cover and the rotor of the motor/generator. The rotor of the motor/generator is supported by either the torque converter or an engine crankshaft or by any two of the torque converter, a motor housing and the crankshaft. The rotor is not affected by the torque converter and the efficiency of the motor is not reduced.