An electrical motor includes a motor case inside which an inner space is formed, a bearing disposed so as to pass through a wall of the motor case, a rotor shaft rotatably supported by the bearing, and an earth conductor fixed with the motor case and provided with a frame and an electrical conductor provided on the frame. The frame has an annular inner circumferential surface along an outer circumference of the rotor shaft and is fixed with the motor shaft. The electrical conductor is disposed on the inner circumferential surface of the frame so as to slidably contact its end with the rotor shaft. A bypass flow passage is provided between the earth conductor and the motor case. The inner space is communicated with an outside of the motor case via the bypass flow passage. According to the motor, its inside can be cooled without damaging the earth conductor.