Heat exchanger

A heat exchanger uses a refrigerant acting under a high pressure, such as carbon dioxide, as a refrigerant. The heat exchanger includes first (10) and second (20) header pipes arranged a predetermined distance from each other and parallel to each other, each having at least two chambers (12,14,22,24) independently sectioned by a partition wall, a plurality of tubes (50) for separately connecting the chambers of the first (10) and second (20) header pipes, facing each other, wherein the tubes (50) are divided into at least two tube groups (51,52), each having a single refrigerant path, a refrigerant inlet pipe (30) formed at the chamber disposed at one end portion of the first header pipe (10), through which the refrigerant is supplied, a plurality of return holes (29) formed in the partition wall to connect two chambers adjacent to each other, through which the refrigerant sequentially flows the tube groups (51,52), and a refrigerant outlet pipe (40) formed at the chamber of one of the first and second header pipes connected to a final tube group of the tube groups along the flow of the refrigerant, through which the refrigerant is exhausted.