A driving force transmission device for four-wheel-drive vehicle based on the two-wheel drive of front wheels is provided. In the case of the two-wheel drive of front wheels, a multi-disc clutch mechanism for controlling the driving force distribution to a rear wheel output shaft, and a disconnection/connection mechanism for disconnecting and connecting a rear wheel differential and a right rear wheel drive shaft are provided, and in the two-wheel drive of front wheels, the dragging torque of the multi-disc clutch mechanism is made smaller than the friction torque of a rear wheel driving force transmission section, and the front wheel differential and the right rear wheel drive shaft are disconnected by the disconnection/connection mechanism, thereby the rotation of the rear wheel driving force transmission section is stopped.