A refrigerant circuit includes an auxiliary heat exchanger for adjusting the temperature of refrigerant, a compressor, a condenser, an expansion valve, and an evaporator. The auxiliary heat exchanger selectively operates through a plurality of switch valves. Thus, the temperature of the refrigerant is efficiently managed according to situations, thereby improving cooling and warming performance. An integrated thermal management system includes the auxiliary heat exchanger configured to exchange heat with outside air, thereby efficiently managing the temperature of the refrigerant and simplifying the structure thereof.