POWER TRANSMISSION UNIT

To achieve a size reduction while making it possible to mold a case housing an axle and a gear mechanism by casting in an electric-vehicle power transmission unit that drives right and left wheels with a single electric motor. [Solution] A power transmission unit includes a motor case that is provided on the same side as a second axle with respect to a center between a first axle and the second axle , separated to right and left, in a right-left direction and that houses the electric motor , a first axle case housing a reduction gear mechanism , a differential gear mechanism , and the first axle , and a second axle case that is fixed to the first axle case in a separable manner and houses the second axle .