A vehicle 1 has a torque coupling 8, which is located in a driving power transmission system for transmitting the torque of an engine 2 to front and rear wheels 13f, 13r. The torque coupling 8 changes the torque distribution by adjusting the frictional engaging force of an electromagnetic clutch 16. The vehicle 1 also has a 4WD ECU 21 (CPU), which controls the operation of the torque coupling 8 based on the driving state. The 4WD ECU 21 (CPU) estimates a transfer case oil temperature Tptu. When the transfer case oil temperature Tptu is higher than or equal to a first predetermined transfer case oil temperature KTptu1, the 4WD ECU 21 executes overheat prevention control. When the deviation ΔA between an estimated vehicle acceleration Ae, which is computed based on a predetermined vehicle weight M and a driveline torque τd of the engine 2, and the actual vehicle acceleration Av is greater than or equal to a first predetermined deviation KΔA1, the 4WD ECU 21 (CPU) estimates the transfer case oil temperature Tptu to be higher. This allows the control mode of the torque coupling 8 to be smoothly switched to the overheat prevention control.