The heat exchanger is provided with a body, multiple heat transfer tubes (20) which are arranged inside of the body, and multiple support plates (30) which are arranged at intervals along the longitudinal direction of the heat transfer tubes (20) and in which multiple tube insertion through-holes (40) for inserting the multiple heat transfer tubes (20) are formed. Between two support plates (30) adjacent in the longitudinal direction among the plurality of support plates (30), the shapes of the tube insertion through-holes (40) for one heat transfer tube (20) are different.