Abstract: A heat exchanger is provided. The heat exchanger may include a plurality of refrigerant tubes extending in a horizontal direction, at least one fin coupled to the plurality of refrigerant tubes, a vertically oriented header coupled to corresponding ends of the plurality of refrigerant tubes, the header distributing refrigerant into the plurality of refrigerant tubes, and a partition device that partitions an inner space of the header, the partition device including at least two through holes that guide refrigerant into the plurality of refrigerant tubes.