To provide a device which can have compact lateral dimensions, which is excellent in mountability, which has a less number and less kinds of components, which is small-sized and lightweight, which is interchangeable with a conventional differential device, which is advantageous in manufacturing cost, with can facilitate the adjustment and the setting for bypass torque, which has a high degree of control accuracy and which is highly durable.

A left and right device force allocating device 7 (12) comprises a differential mechanism 44 composed of a bevel gear, and first and second gears 58, 59 are fixed to a differential casing 51 while third and fourth gears 58, 59 are fixed to a drive shaft 17. Fifth to eight gears 63 to 66 meshed with the gears on one and the same center rotary axis are arranged on one and the same rotary center axis in parallel with the former rotary center axis. The gear ratios of the gear trains are set to 0.9, 1.0, 0.9, 1.0, respectively. The fifth gear 63 and the eighth gear 66, and the sixth gear 64 and the seventh gear 65 are disengageably engaged by a first hydraulic multiple disc clutch 78 and a second hydraulic multiple disc clutch 74, respectively. Further, the engagement of these hydraulic multiple disc clutches 78, 74 is controlled so as to allocate the drive power between left and right wheels.