The present invention relates to a
heat exchanger (100) that includes a first
heat exchanger core (1) and a second
heat exchanger core (2) arranged side by side. The first heat exchanger core (1) includes a first main segment (10, 10A, 10B), a first connection segment (19, 19A, 19B) connected with the first main segment (10, 10A, 10B), and a first header (13). The first main segment (10, 10A, 10B) includes a plurality of first heat exchange tubes (11, 11A, 11B) arranged in a second direction (2) perpendicular to a first direction (D1). The second heat exchanger core (2) includes a second main segment (20), a second connection segment (29) connected with the second main segment (20), and a second header (23). The second main segment (20) includes a plurality of second heat exchange tubes (21) arranged in the second direction (D2). The first main segment (10, 10A, 10B) includes a first wind resistance region (17, 17A, 17B) and a second wind resistance region (18, 18A, 18B) arranged in a third direction (D3) perpendicular to the first direction (D1) and the second direction (D2), the second wind resistance region (18, 18A, 18B) being adjacent to the first header (13), and a wind resistance of the second wind resistance region (18, 18A, 18B) is smaller than that of the first wind resistance region (17, 17A, 17B), thereby improving the performance of the heat exchanger (100).