A heat exchanger includes a plurality of tubes having refrigerant flowing therein and arranged to exchange heat with outside air; and a header having a chamber adapted to distribute the refrigerant to the plurality of tubes, wherein the header includes, a base wall having a plurality of tube insertion holes into which the plurality of tubes are inserted, and a partition wall integrally formed with the base wall and configured to divide the chamber into a plurality of sections corresponding to the plurality of tubes. This structure helps reduce the number of parts of the heat exchanger, simplify processing and assembling, and improving the heat transfer performance by improving the distribution of the refrigerant.