This invention relates to an air conditioning device which regulates the temperature of an airflow exhausted from the space in a cooling/heating air conditioning object (such as inside of a room or vehicle) to the external through an external heat exchanger disposed externally for heat exchanging so as to allow the exhausted airflow to even the temperature of the fluid flowing through the heat exchanger by means of the temperature differentiation of the two fluids, thereby enhancing the efficiency of the air conditioning device while reducing the energy consumption of the air conditioning device.