To provide an inexpensive final reduction gear for a vehicle, which can promote warming-up of lubricating oil and reduce agitation resistance of the lubricating oil by a ring gear with a simple structure and prevent the lubricating performance of a lubricating element such as a bearing from being deteriorated.

A final reduction gear 6 is partitioned into a sub-reservoir 28B positioned in front of the vehicle 1 and a main reservoir 28A positioned in the rear of the vehicle 1, in which the bottom of the ring gear 14 is immersed by a partition part 29. A solenoid valve 68 communicates between the main reservoir 28A and the sub-reservoir 28B or blocks them by a thermoelectric conversion module 61 which generates electric power by a temperature difference between the lubricating oil stored in the main reservoir 28A and the lubricating oil stored in the sub-reservoir 28B.