An air conditioner is arranged so as to be able to accurately judge a refrigerant filling state within the air conditioner regardless of environmental and installation conditions. The air conditioner has a computing section 102 for computing a condenser liquid phase area ratio that is a value related to an amount of liquid phase portion of the refrigerant within a high pressure-side heat exchanger, based on refrigerant condensation temperature of the high pressure-side heat exchanger, outlet super-cooling degree of the high pressure-side heat exchanger, intake air temperature of the high pressure-side heat exchanger, a difference of enthalpy of inlet and outlet of the high pressure-side heat exchanger and specific heat at constant pressure of a refrigerant solution at the outlet of the high pressure-side heat exchanger and a judging section 106 for judging the refrigerant filling state within the air conditioner based on a comparison of the value computed by the computing section 102 with a predetermined value.