Abstract: A heat exchanger includes a plurality of heat exchange tubes stacked with a gap through which a first fluid can pass. The heat exchange tube includes: an internal flow path through which a second fluid for exchanging heat with the first fluid and which includes a folded portion; a plurality of slits provided between two flow path portions in the internal flow paths, the two flow path portions each extending from the folded portion and facing each other at an interval; and a plurality of protruding support portions in contact with another adjacent heat exchange tube to form the gap. As viewed in a stacking direction of the plurality of heat exchange tubes, at least one of the plurality of slits extends in a state where a center in an extending direction thereof deviates from a straight line connecting the two adjacent protruding support portions.