A heat exchanger of the present disclosure includes a plurality of fin tubes; in which refrigerant channels through which refrigerant flows are formed and which are arranged to be spaced apart in one direction; and a pair of headers configured to communicate with the refrigerant channels of the fin tubes, wherein each of the fin tubes of the plurality of fin tubes includes refrigerant channels through which a refrigerant can flow, a header hole through which the refrigerant can flows, and a header collar protruding in one direction from an edge of the header hole, wherein the one header collar of a respective fin tube of the plurality of fin tubes is inserted into another the header hole of the adjacent fin tube to the one respective fin tube, and wherein the pair of headers are configured to communicate with the refrigerant channels of the fin tubes.