To preclude air-conditioning performance from being affected even when an engine speed for vehicle traveling is varied.

A refrigerating cycle is formed by being provided with a compressor 11 driven by an electric motor to compress a gaseous refrigerant to be fed, a four-way valve 12 for changing over refrigerant-flowing directions, a heat-exchanger 13 served as both heat-absorption and heat-exhaustion for absorbing or exhausting heat in response to the refrigerant-flowing directions, an expansion valve 14 for pressure-reducing and expanding the liquid refrigerant of high temperature and high pressure, and an evaporator 17 and a condenser 18 arranged to switch selectively passing of the refrigerant by providing solenoid opening and closing valves 15, 16 respectively to conduct heat-exchange with respect to air-conditioning air.