Provided is a heat exchanger equipped with a heat-exchanger fin that is capable of: preventing the formation of frost as soon as possible during operation of a heater; under conditions where condensation is likely to form on a fin surface, quickly removing water droplets by causing the droplets of condensed water to contact a hydrophilic membrane; and as a result, maintaining a favorable heat exchange function without increasing ventilation resistance. A heat exchanger provided with a heat-exchanger fin being made from an aluminum plate and having a hydrophilic membrane and a cross-linked water-repellent membrane that exhibits a frost-suppressing effect, wherein: the surface area constituted by the cross-linked water-repellent membrane in a 10mm x 10mm square area in an unspecified location on the surface of the heat-exchanger fin is 20-80%; the cross-linked water-repellent membrane contains a resin (A) having a fluorine-atom-containing group, a denatured epoxy resin (B) containing a quaternary ammonium base, and an amino resin (C); and an aqueous water-repellent coating composition from which the heat exchanger is formed has 1-30 parts by mass of solid content of the resin (A), and 100 parts by mass in total of the solid content of the resin (B) and the resin (C).