A heat exchanger according to a concept of the disclosure includes an inlet pipe, an outlet pipe, and a connecting pipe connecting a first header to a second header, to perform heat exchange while a refrigerant flows in one direction of a up direction or a down direction in the heat exchanger to thereby improve circulation of the refrigerant, wherein each of the first header and the second header includes a plurality of partitioned chambers therein to distribute the refrigerant several times according to a flow of the refrigerant passing through each chamber, thereby improving distribution and mixing of the refrigerant.