A fin-tube heat exchanger includes a plurality of fins 1 for forming flow paths of a gas therebetween and a heat-transfer tube 21 extending through the plurality of fins to allow a fluid to flow therethrough for heat exchange with the gas. Each of the fins includes a plurality of first inclined portions 6 that incline with respect to a direction of airflow so as to form at least one ridge portion 3, a plurality of tube-surrounding portions 5 formed around the heat-transfer tube that extend through each of the fins at a first position and a second position spaced away from each other in a direction of gravitational force, and a plurality of second inclined portions 7 that connect the tube-surrounding portions and the first inclined portions together. Each of the first inclined portions has a groove portion 8 defined in a surface thereof to connect the second inclined portion at the first position to the second inclined portion at the second position. By this configuration, condensed water is smoothly introduced downwardly in the direction of gravitational force along the groove, thereby enhancing the drainage performance.