A heat exchanger, comprising: - a plurality of fins each having a main surface and a plurality of through holes (13ca, 13cb) arranged as aligned along a first direction in the main surface, and arranged as stacked at a distance from one another; and - a heat conduction pipe passing through the plurality of through holes (13ca, 13cb) in each of the plurality of fins, - at least one fin among the plurality of fins including - a cut and raised slit formed in a region adjacent to at least one through hole (13ca, 13cb) of the plurality of through holes (13ca, 13cb) in the first direction and having a tunnel-shaped hole (13ba 1, 13bb 1, 13bc 1) extending in a second direction intersecting the first direction, and - a cut and raised wall portion located in the second direction of the cut and raised slit, protruding toward the main surface of the at least one fin, and extending along the first direction, - wherein the plurality of through holes (13ca, 13cb) include a plurality of first-stage through holes arranged as aligned in the first direction and a plurality of second-stage through holes arranged as aligned in the first direction and arranged at a distance from the plurality of first-stage through holes in the second direction, characterized in that - the hole pitch between the plurality of first-stage through holes is smaller than the hole pitch between the plurality of second stage through holes, and in that - all cut and raised wall portions are arranged to be displaced toward a downstream side in a direction of flow of combustion gas from a virtual line connecting centres of the plurality of the first-stage through holes arranged as aligned in the first direction, wherein the first-stage through holes are arranged on a downstream side of the second-stage through holes. - a plurality of fins each having a main surface and a plurality of through holes (13ca, 13cb) arranged as aligned along a first direction in the main surface, and arranged as stacked at a distance from one another; and - a heat conduction pipe passing through the plurality of through holes (13ca, 13cb) in each of the plurality of fins, - at least one fin among the plurality of fins including - a cut and raised slit formed in a region adjacent to at least one through hole (13ca, 13cb) of the plurality of through holes (13ca, 13cb) in the first direction and having a tunnel-shaped hole (13ba 1, 13bb 1, 13bc 1) extending in a second direction intersecting the first direction, and - a cut and raised wall portion located in the second direction of the cut and raised slit, protruding toward the main surface of the at least one fin, and extending along the first direction, - wherein the plurality of through holes (13ca, 13cb) include a plurality of first-stage through holes arranged as aligned in the first direction and a plurality of second-stage through holes arranged as aligned in the first direction and arranged at a distance from the plurality of first-stage through holes in the second direction, characterized in that - the hole pitch between the plurality of first-stage through holes is smaller than the hole pitch between the plurality of second stage through holes, and in that - all cut and raised wall portions are arranged to be displaced toward a downstream side in a direction of flow of combustion gas from a virtual line connecting centres of the plurality of the first-stage through holes arranged as aligned in the first direction, wherein the first-stage through holes are arranged on a downstream side of the second-stage through holes.