Present invention is to provide a heat pump type airconditioner wherein during warming, a refrigerant is successively circulated through a compressor--an indoor heat exchanger--an outdoor heater equipped with a refrigerant heating mechanism--the compressor and wherein a bypass circuit it disposed which includes a solenoid valve for the communication between the delivery side and suction side of the compressor; characterized in that a refrigerant temperature at an outlet of the refrigerant heating mechanism is sensed, that the solenoid valve is opened to bypass the refrigerant at the starting of the operation, that is, at the starting of the compressor, while the solenoid valve is closed when the refrigerant temperature has reached a predetermined temperature owing to heating and that the refrigerant heating mechanism is turned OFF after the refrigerant temperature has risen up to a predetermined temperature.