PURPOSE: To improve comfortableness in a car room by heating the car room inside rapidly at the time of coldness.

CONSTITUTION: A control part 6a of a controller 6 sets a watt number of a heating wire 5k of heating plate 5 on the basis of an ambient temperature at the vicinity approximated to a driver detected by an ambient temperature sensor 1, an outside air temperature detected by an outside air temperature sensor 2, and a temperature regulating control map 6B showing corresponding relations with the watt number of the heating wire 5k of the heating plate 5, outputting a watt number selective signal conformed to the set watt number, and a heater selector switch 10 is connected to either of terminals 5p, 5q and 5r. With this constitution, rapid heating control on the basis of heat generated by the heating wire 5k of the heating plate 5 is carried out, then at a point of time when a water temperature of engine cooling water is reached to the specified temperature (60°C), it shifts to ordinary heating control.