In the present invention, a receiving space is formed inside by the combination of the first member and the second member, and the header fitting portion is formed by inserting the header into the open ends formed by combining the first member and the second member. case; A plurality of tubes provided inside the case, arranged to be spaced apart from each other, and having open ends disposed at the header fitting portion of the case, and forming a flow path through which air flows; A plurality of fins interposed between the tubes and forming a flow path through which coolant flows between the tubes; And a pair of headers respectively inserted into and coupled to the header fitting portions of the case, a plurality of tube insertion holes formed therein, and a tube inserted into and coupled to the tube insertion hole. Consisting of including, it relates to a heat exchanger that is easy to assemble by inserting a core formed by stacking tubes and fins in the case.