A heat exchanger is provided that may include a shell; a first pipe that guides a first fluid into the shell; a tube, through which a second fluid that exchanges heat with the first fluid may pass; a second pipe, through which the first fluid is guided outside of the shell; and a base including a fastening portion to which the shell may be fastened and a support portion that supports the fastening portion. The fastening portion may have a tube hole, through which the tube may pass, and a pipe hole, through which at least one of the first pipe or the second pipe may pass, so that it is possible to increase availability of space at a side of and above the shell, and at least one of the first pipe, the second pipe, or the tube may be protected by the base, resulting in high reliability.