It is an object of the present invention to provide a hybrid differential gear device achieving the small and light devices as a whole and easy assembling of a differential case.A hybrid differential gear device has a first differential gear mechanism 2 and a second differential gear mechanism 3. The first differential gear mechanism 2 has a plurality of planetary gears 5 as an input element, a sun gear 6 engaging with the plural planetary gears 5 as a first output element, and an internal gear engaging with the plural planetary gears 5 as a second output element. The second differential gear mechanism 3 has side gears 14R, 14L connected respectively to a right and a left front tire wheel, pinion gears 12, 13 engaging with the side gears 14R, 14L, and a pinion gear shaft 15 supporting rotatably the pinion gears 12, 13. The pinion gear shaft 15 is supported non-rotatably and movably to a direction of a rotational axis of a differential case 4.