The present invention comprises: a heat exchanger constituent (2) provided with header pipes (4, 6) disposed parallel to each other, a plurality of tubes (8) disposed between the header pipes so as to be communicated with both header pipes, and fins (10) disposed between adjacent tubes, in which layered tubes and fins constitute a core part (12) for heat exchange; a plurality of heat exchanger constituents being disposed side by side in the layering direction of the tubes and fins, and being provided with joints (16, 18) for connecting end parts (4a, 6a) of mutually opposing header pipes of adjacent heat exchanger constituents with each other by fitting, and side plates (20, 22, 40, 42, 46, 48) for joining edge parts (12a, 12a) of mutually opposing core parts of adjacent heat exchanger constituents with each other by linkage.