Heat exchanger and water heater

A heat exchanger, comprising:

• a plurality of fins each having a main surface and a plurality of through holes arranged as aligned along a first direction in said main surface, and arranged as stacked at a distance from one another;
• and
• a heat conduction pipe passing through said plurality of through holes in each of said plurality of fins,
• at least one fin among said plurality of fins including
• a cut and raised slit formed in a region adjacent to at least one through hole of said plurality of through holes in said first direction and having a tunnel-shaped hole extending in a second direction intersecting said first direction, and
• a cut and raised wall portion located in said second direction of said cut and raised slit, protruding toward said main surface of said at least one fin, and extending along said first direction.