Heat exchangers 40, 40a, 40b for performing heat exchange between a refrigerant and air include fins 45, 45a, 45b for heat transfer, each of which has fine pores each having a diameter ranging from 1 to 3.5 nm for adsorbing water contained in the air by a capillary condensation phenomenon. Preferably, the fine pores are distributed having a different diameter in accordance with the position of the fins 45, 45a, 45b on the surface.