Abstract: Provided is a heat exchanger comprising a flat perforated heat transfer pipe having multiple refrigerant flow paths substantially parallel to each other, a fin provided with an insertion hole into which the flat perforated heat transfer pipe is to be inserted, and headers connected to ones of the refrigerant flow paths at both end portions in a width direction of the flat perforated heat transfer pipe, wherein the refrigerant flow paths are separated by at least four partition walls in the flat perforated heat transfer pipe, and are arranged in the width direction, the flat perforated heat transfer pipe is expanded and joined to the insertion hole, and ones of the refrigerant flow paths arranged at both end portions in the width direction have a greater width than those of other refrigerant flow paths.