PURPOSE: To improve the assembly workability and economical efficiency with meshing adjustment made possible by slight turning of a differential side bearing by eccentrically placing its inner race in relation of an outer race.

CONSTITUTION: To adjust meshing a drive bevel pinion 7 with a drive bevel gear 8, a differential side bearing 2 is turned by a slight angle θ1 in the clockwise or counter clockwise direction. Then the bevel gear 8 is moved to a side of or an opposite side to the bevel pinion 7 by a distance P. Thus by slightly turning the side bearing 2, meshing can be easily adjusted. After this adjustment, a differential side bearing cap 4 is fixed. Thus by adjusting the meshing, the cap 4 is only required to be removed because of no necessity for replacing a shim 10, and assembly work of a differential gear device is smoothly performed by eliminating the necessity for disassembling the other parts.