A position detecting purpose permanent magnet 51 constituting a position detection sensor is installed at an opposite side to an output side of a rotational shaft 45 of a rotor housed within a motor housing 11A. A GMR element 56 which constitutes the position detection sensor and a position detection circuit thereof are installed on a side of a motor cover 48 on which a position detection purpose permanent magnet 51 is arranged. GMR element 56 is arranged on a position opposed against the position detection purpose permanent magnet. Thus, since the GMR element and the position detection purpose permanent magnet is installed, a mutually positioning assembly (attachment) accuracy can be improved. In addition, since the electric power conversion circuit and both of the GMR element and its position detection circuit are kept away, such an effect that an accurate detection signal can be obtained can be achieved.