A double pinion planetary gear unit includes a first sun gear, a second sun gear, a plurality of short pinions, a plurality of long pinions, a ring gear and a carrier. The carrier includes a first flange portion that supports an end side of the short pinions and an end side of the long pinions, a cylindrical portion that is connected to the first flange portion and that forms a cover for an outer peripheral side where the short pinions and the long pinions mesh with each other, a second flange portion that supports another end side of the long pinions, and a plurality of bridge portions that extend from the second flange portion toward the short pinions and that support another end side of the short pinions.