A differential case of a differential gear has a pair of openings formed facing each other on an axis X that is orthogonal to a rotational axis of a differential ring gear. A reservoir plate (partitioning member) that partitions a space in a transmission case into a differential chamber and a working oil storage chamber has a tubular portion that surrounds a part of the differential case. The tubular portion has a discharge hole formed so as to be able to face the pair of openings as the differential case is rotated about the rotational axis.