A power converter that is arranged in series with a motor to form a unitary structure through which an output shaft extends is provided with a plurality of coolers and a power semiconductor module mounted on a cooling surface of at least one of the plurality of coolers to supply electric power to a motor. Each of the plurality of coolers is disposed along an extending direction radially extending from an output shaft to be perpendicular to the output shaft. The cooling surface is provided along such an extending direction.