An end surface portion 8a of a gear housing 8, which is located on a motor unit 2 side of the gear housing 8, is opposed to the motor unit 2 and laterally extends. A brush holder 10 includes a plate portion 13 that is opposed to the end surface portion 8a. A case 15, which receives the control circuit board 14, is formed separately from the plate portion 13. A receiving through hole, through which the circuit board receiver 15 is receivable, is formed in the plate portion 13. The case 15 is constructed to be positionable next to the yoke 5 in a state where the case 15 is received through the receiving through hole. The yoke 5, the gear housing 8, the brush holder 10, the control circuit board 14 and the case 15 are assembleable in a direction parallel to an axial direction of the motor unit 2. The control circuit board 14 projects from the gear housing 8 on the motor unit 2 side, and a projected part of the control circuit board 14, which projects from the gear housing 8 on the motor unit 2 side, is received in the case 15. In this way, in the motor that integrally includes the motor unit, the speed reducing unit and the control circuit board, the gear housing of the speed reducing unit can be made compact, and the assembly work can be simplified.