A heat exchanger includes: a receiving tube into which a fluid is introduced; a discharge tube for discharging a heat-exchanged fluid outwardly; a plurality of fins disposed between the receiving tube and the discharge tube, being bent at regular intervals so that air can pass at an outer circumferential surface thereof, and having a guide unit for guiding condensate water condensed at the surface thereof in one direction; and a tube disposed between the fins for heat-exchanging between a fluid passing therethrough and air passing the outer circumferential surface of the fin, and having a condensate water discharge path for discharging downwardly the condensate water guided by the guide unit. A condensate water remaining phenomenon between the fins can be reduced, and thus, the heat exchanging performance is improved.