Heat exchanger for stirling machine, method for manufacturing heat exchanger, and regenerator

A regenerator for circulating a fluid in an internal space, the regenerator comprising:

• a heat storage that is capable of storing heat of the fluid;
• and
• a housing that surrounds the heat storage, wherein
• the heat storage and the housing are continuously connected to each other and provided in one piece,
• the heat storage includes a plurality of side elements that are continuously connected to each other in a three-dimensional manner and provided in one piece, and
• each of the plurality of side elements has a plate shape in which a projected area as viewed from a second direction intersecting with a first direction is larger than a projected area as viewed from the first direction, the first direction being a flow direction of the working fluid.