In an electric motor apparatus including an electric motor (13), a speed-reduction mechanism (14) which transmits motive power of the electric motor (13), a housing (15) which accommodates the speed-reduction mechanism (14) and the electric motor (13), and a yoke (16a) fixed to an outer portion of the housing (15), the housing (15) is provided with a concave portion (21), a holding hole (18a), and an accommodation chamber (15a). A connector unit (25) is moved along the first direction and installed to a concave portion (21). A brush holder (26) is moved along the second direction and installed to the holding hole (18a). The speed-reduction mechanism (14) is moved along the first direction and accommodated in the accommodation chamber (15a). The yoke (16a) is moved along the second direction and fixed to the housing (15). Therefore, no restriction is imposed on the routing of an external connector connected to the connector unit (25).