The motor has a rotor (50) penetrated into a stator (40) which is covered by front and rear face covers (60,70). A cooling water flow path is arranged around the stator in a concentric manner inside a tubular housing (30). The inflow opening of the cooling water is provided on the front cover. An outlet formed in an axial direction in the housing accumulates the discharge of the cooling water circulating through the cooling water flow path.
