Heat releasing portions (15A, 15B) that release and transmit heat generated at at least a power conversion circuit unit (16) to a motor housing (11) are formed at an end surface wall (15) of the motor housing (11) which is an opposite side to an output shaft portion (14) of a rotation shaft (23) of the electric motor. Positioning protrusions (16P), as positioning portions whose positions are fixed by board fixing portions (26A, 26B) formed at the end surface wall (15) of the motor housing (11), are formed at a part of synthetic resin that covers the power conversion circuit unit (16). With this, positioning of the power conversion circuit unit (16) can be made using the existing board fixing portions (26A, 26B), and an outward appearance size can be reduced without newly adding a special positioning mechanism.