Provided is heat exchanger in which a rib of a core plate has a shape that is recessed from a flat surface of a flat body portion, and the rib is provided with: a rib bottom part including a bottom line that is recessed from and parallel to the flat surface of the flat body portion; and a rib inclination part that is positioned between the rib bottom part and a flat part. The rib is positioned so that the rib inclination part overlaps, in the tube stacking direction, the edge of the tube in the tube width direction.