A temperature control device for a vehicle cabin comprises a duct which communicatively connects, at least, inside the vehicle cabin and the external atmosphere; a damper provided within the duct and for shutting off flow of air inside and outside the vehicle cabin; drive means for driving the damper to open and close; a fan to produce the air flow within the duct; a fan motor to actuate and drive the fan; detecting means to detect temperature changes within the vehicle cabin; and a power source separately provided from an ordinary power source and for supplying power to the fan motor. A temperature increase within the vehicle cabin above a predetermined temperature is detected by the detecting means, then electric power is supplied to the fan motor from the separately provided power source, and the temperature within the vehicle cabin is controlled in utilization of the duct, in which the damper is in an open state.