PURPOSE: To prevent decrease of an output shaft torque of a wheel at which idle run has occurred by providing a differential gear with a continuously variable transmission capable of speed reduction, constant speed, and speed increase, and connecting a first output shaft of the differential gear with a first transmission shaft of the continuously variable transmission, and a second output shaft of the differential gear with a second transmission shaft of the continuously variable transmission.

CONSTITUTION: A mechanical type differential gear 1 is provided with a torque distribution control device 11 including a continuously variable transmission (CTV) 20, and if a right wheel runs idly, an output shaft 7 which is going to rotate at a high speed is braked by the CVT 20 through a connecting means 13. A produced load torque T20 is transmitted through the CVT 20, a transmission shaft 24 and a connecting means 12 to an output shaft 6 to increase the torque, and rotation numbers W1, W2 approach each other to put the torque of the output shafts 6, 7 at the torque T20, so the torque of a power transmitting shaft 8 is 2×T20, thereby the output of an engine can be applied effectively.