To effectively cool down a stator coil generating a large amount of heat therein, a heat conductive member is disposed between a coil end and a metal frame in contact therewith. Heat generated in the stator coil is conducted to the heat conductive member and the heat conductive member is cooled down by cooling air from a cooling fan. Heat form the conductive member is also transferred to the metal frame, thereby the stator coil is further cooled. Even when the coil end cannot be cooled directly by the cooling air because the coil end is short, the coil end is effectively cooled by means of the conductive member. A corrugated fin made of a heat conductive metal plate such as an aluminum plate is preferably used as the heat conductive member. Fins formed on the metal frame may be also used as the heat conductive member. The heat conductive member may be disposed at both ends of the stator coil to enhance cooling effect.