To improve the durability of thrust washers externally inserted into the end part of a pinion shaft.

An about V-shaped oil discharge grooves 17 spreading out from the inner peripheral edge of a through hole 4b toward the outer peripheral edge of a carrier plate 3 is formed on the bearing surface of the carrier plate 3 facing the axially outside thrust washer 14 out of two thrust washers 14 externally inserted in the end part of a pinion shaft 6. A pin 10 is arranged at the center part of the V-shape of the oil discharge grooves 17 formed on the bearing surface of the carrier plate 3, and thus the oil discharge grooves 17 are adapted to be not overlapped with the pin 10 in the direction of thickness of the carrier plate 3.