Disclosed in an air conditioner including a control box having a space formed therein, a PCB arranged to form an air circulation passage in the space, the PCB having a plurality of electric components mounted thereto, a cooling module for making a first electric component of the plurality of electric components to heat exchange with refrigerant, and a circulating fan arranged in the air circulation passage to make air to flow to a second electric component of the plurality of electric components after cooled by the cooling module, thereby dissipating heat from an inside of the control box with a mixed cooling system of a refrigerant cooling system and an air cooling system, efficiently.