A differential gear mechanism includes a housing, first and second sun gears each including an external gear portion, and first and second planetary gears. The first and second sun gears include axial end surfaces pressed against contact surfaces provided at the housing by the first and second sun gears by means of thrust forces generated at engagement surfaces between the external gear portions and the planetary gears. Each of the sun gears includes a first portion having the external gear portion, a second portion, and a thrust force generating mechanism for generating thrust forces at the first portion and the second portion. A direction of the thrust force generated at the first portion by the thrust force generating mechanism is specified to be equal to a direction of the thrust force generated at the first portion by means of the engagement between the external gear portion and the planetary gear.