Each cross-section of the connector member assembling hole and the assembly main body 51a in a direction intersecting the insertion direction has a point-symmetrical circular shape with the insertion shaft center FC as the center. A pair of connector-side female terminals 57a, opposed to each other with the insertion shaft center FC as the center, is provided at the distal end side in the insertion direction of the assembly main body 51a, and a pair of brush-side male terminals, opposed to each other with the insertion shaft center FC as the center and to which the connector-side female terminals 57a are connected, is provided to a portion of the brush holder opposite to the connector member assembling hole. Therefore, it is possible to insert the connector member 50 into the gear case in the state of being rotated by 180 degrees about the insertion shaft center FC, and it is possible to cope with arrangement needs which are different by 180 degrees in a connection direction of the external connector, using one connector member 50.