The present invention comprises: a plurality of first tubes and a plurality of second tubes in which a refrigerant passes through and which are formed so as to be long in the vertical direction, respectively, and spaced from each other such that air flows therebetween; and fins respectively coming into contact with the first tubes and the second tubes, wherein the plurality of second tubes are positioned to be spaced from each other at the slip stream of the plurality of first tubes in the direction in which the air flows, the fins include: a first louver group comprising a plurality of louvers positioned among the plurality of first tubes and spaced from each other in the direction in which the air flows; and a second louver group comprising a plurality of louvers positioned among the plurality of second tubes and spaced from each other in the direction in which the air flows, and the plurality of louvers of the first louver group are formed such that the intervals thereof from the other adjacent louvers gradually narrow toward the slip stream of the direction in which the air flows and the plurality of louvers of the second louver group are formed such that the intervals thereof from the other adjacent louvers gradually expand toward the slip stream of the direction in which the air passes, thereby minimizing the concentrated formation of frost on the front part of a heat exchanger in the direction in which the air passes through the heat exchanger and maximally delaying the time at which the front part of the heat exchanger is blocked by the frost.