There is provided a heat exchanger of an air conditioning device capable of improving heat exchange efficiency in heat transfer tubes arranged in downstream rows in an airflow direction to enhance cooling capacity. In the heat exchanger of the air conditioning device, a plurality of heat transfer tubes arrayed in three or more rows in the airflow direction are provided, and a refrigerant is distributed to a plurality of paths to be supplied to the heat transfer tubes, and the heat exchanger is used as a evaporator during cooling operation. The plurality of paths include a most downstream path made up of only the heat transfer tubes in a most downstream row in the airflow direction, and an upstream path made up of only the heat transfer tubes in a plurality of rows arranged on an upstream side of the most downstream path.