A motor power train which includes a reducer for amplifying motor drive torque, a differential device with a clutch mechanism and a differential gear unit to allocate the drive torque to wheels, and a casing for housing them. The reducer includes a first shaft as an input shaft; a second shaft to which the drive torque is transmitted form the first shaft; a first reduction gear set with a first gear on the first shaft and a second gear on the second shaft; and a second reduction gear set with a third gear on the second shaft and a fourth gear provided on the clutch mechanism of the differential device. The fourth gear and a large-diameter portion of the differential gear unit are offset in axial position without overlapping.