To dissolve a problem that a water-cooled motor is formed by combining a pump from with the outer peripheral side of a motor frame and cooling is effected by a flow of water to a water passage between the motor frame and the pump frame but water leaks through a space between the motor frame and the pump frame and a seal part between the motor frame and a casing cover, water is poured on a motor winding, and deterioration of insulation and a damage due to leakage of electricity are apt to occur.

In a water-cooled motor, a motor winding protection cover 19 consisting if a cap-form cover and a ring-form elastic substance 15 is situated in a motor frame 1. The hole 19a of the disc part 11 of the cap-form cover is fitted in the housing 9 of the bearing A7 of a motor. The end part of the cylinder part 13 of the cap-form cover is fitted in the ring-form groove 15a of the ring-form elastic substance A15 and nipped by both the inside and the outside. The ring-form inner pleats 21a and the outer pleats 21b of the ring-form elastic substance 15 are brought into contact with the plane of a stator 23.