An electric power steering electric motor apparatus includes: an electric motor including: a motor housing; a stator; a rotor; and a power supplying portion that supplies electric power to the stator; and a controlling unit including a driving circuit that supplies electric power to the electric motor; a connecting portion; a controlling circuit; and a case that covers the driving circuit and the controlling circuit, the electric motor and the controlling unit being mounted coaxially onto a gear housing that reduces rotational speed of the electric motor so as to position the controlling unit on a side near the gear housing, and the connecting portion being connected to the power supplying portion inside the case through an opening portion formed on the case, and being positioned and held by an insulating member so as to be insulated from the case and the motor housing.