An air conditioner is switchable between a cooling mode and a heating mode using highly pressurized hot gas in a refrigerant cycle. During the cooling mode, a controller controls an input electric current to a solenoid to operate the control valve based on a lower pressure side pressure of the refrigerant cycle acting on a pressure sensitive mechanism and a quantity of the input electric current to the solenoid. During the heating mode, the controller controls the input electric current to the solenoid to operate the control valve based not on the lower pressure side pressure of the refrigerant cycle acting on the pressure sensitive mechanism, but only on the quantity of the input electric current to the solenoid.