An ECU estimates the temperatures of the heat generating portions provided in a drive force transmission system, or a transaxle, a rear differential, and a torque coupling, in correspondence with not only the rotational speed (the differential rotational speed) of each heat generating portion and the torque transmission rate of the torque coupling but also the outside temperature detected by an outside temperature sensor. If the estimated temperature of any of the heat generating portions exceeds a respective predetermined temperature, the ECU controls operation of the torque coupling to suppress overheating of the heat generating portion. That is, the temperature of each heat generating portion is accurately detected through a simplified structure and overheating of the heat generating portion is effectively suppressed.