To give rotational friction resistance to side gears to obtain initial torque, by arranging pressurized members to one side or both sides between both side gears and between the respective side gears and a differential case.

Thrust washers 31 are arranged between side gears 13 and 15 and a differential case 3 respectively. Also thrust washers 33 and 35 and a link-like wave plate 37 (pressurized member), with the washers 33 and 35 between, are arranged between the side gears 13 and 15. The left thrust washer 33 and the wave plate 37 are arranged in a housing part 39 formed on the boss part 17 of a side gear 13, and the outer peripheral part of the right thrust washer 35 is placed between the side gears 13 and 15. The wave plate 37 is a spring member with recessed and protruded parts formed alternately in a peripheral direction, and when assembled, is deflected by preload to press the side gears 13 and 15 via the thrust washers 33 and 35 to push the side gears 13 and 15 against the differential case 3 via the thrust washer 13.