To change torque distribution between a front wheel and a rear wheel.

This two-speed driving system for a whole wheel driven vehicle comprises a front differential device 18 having double planetary gears and a power take-off unit 20 for transmitting driving torque to a front wheel set 28 and a rear wheel set 48 of a vehicle. A rear differential device 42a is connected to the power take-off unit and the rear wheel set for supplying driving torque to the rear wheel set. A two-speed driving unit 40 is arranged between the power take-off unit and the rear differential device. The driving unit performs change-over between high range driving operation and low range driving operation. The driving unit is mounted directly on either the power take-off unit or the rear differential device.