An electric power steering electric motor apparatus comprising: an electric motor comprising: a motor housing; a stator that is held by said motor housing; a rotor that is disposed inside said stator so as to be rotatably supported by said motor housing; and a power supplying portion that is connected to said stator to supply electric power; and a controlling unit comprising: a driving circuit that supplies electric power to said electric motor; a connecting portion that is connected to said power supplying portion; a controlling circuit that controls said driving circuit; and a case that covers said driving circuit and said controlling circuit, said electric motor and said controlling unit being mounted coaxially onto a gear housing, housing a speed reducing mechanism that reduces rotational speed of said electric motor so as to position said controlling unit on a side near said gear housing, wherein said connecting portion is positioned and held by an insulating member so as to be insulated from said case and said motor housing, said electric power steering electric motor apparatus being characterized in that: said connecting portion is joined to said power supplying portion inside said case through an opening portion that is formed on said case. a motor housing; a stator that is held by said motor housing; a rotor that is disposed inside said stator so as to be rotatably supported by said motor housing; and a power supplying portion that is connected to said stator to supply electric power; and a controlling unit comprising: a driving circuit that supplies electric power to said electric motor; a connecting portion that is connected to said power supplying portion; a controlling circuit that controls said driving circuit; and a case that covers said driving circuit and said controlling circuit, said electric motor and said controlling unit being mounted coaxially onto a gear housing, housing a speed reducing mechanism that reduces rotational speed of said electric motor so as to position said controlling unit on a side near said gear housing, wherein said connecting portion is positioned and held by an insulating member so as to be insulated from said case and said motor housing, said electric power steering electric motor apparatus being characterized in that: said connecting portion is joined to said power supplying portion inside said case through an opening portion that is formed on said case. a driving circuit that supplies electric power to said electric motor; a connecting portion that is connected to said power supplying portion; a controlling circuit that controls said driving circuit; and a case that covers said driving circuit and said controlling circuit, said electric motor and said controlling unit being mounted coaxially onto a gear housing, housing a speed reducing mechanism that reduces rotational speed of said electric motor so as to position said controlling unit on a side near said gear housing, wherein said connecting portion is positioned and held by an insulating member so as to be insulated from said case and said motor housing, said electric power steering electric motor apparatus being characterized in that: said connecting portion is joined to said power supplying portion inside said case through an opening portion that is formed on said case.