A heat exchanger for a stirling engine 10A of a twin-cylinder α type includes a heat transfer tube group 70A formed with heat transfer tubes 71A causing a working fluid of the stirling engine 10A to flow between a high-temperature cylinder 20 and a low-temperature cylinder 30 arranged linearly and parallel to each other in the stirling engine. The heat transfer tube group 70A includes a rising section G1 extending upward, a falling section G2 extending downward, and a connecting section G3 connecting the rising section G1 and the falling section G2 in a turn-back manner, where the heat transfer tube group 70A is regarded as extending from one end or the other end thereof.