Abstract: A cogeneration system is preferably provided with a Stirling engine that has a pillar-shaped heated head, a burner that faces an end surface of the heated head of the Stirling engine, a first exhaust passage that extends along the side surface of the heated head of the Stirling engine, a second exhaust passage that continues from the first exhaust passage and extends along a side of the first exhaust passage opposite to the Stirling engine, and a first heat exchanger that is arranged on a side of the second exhaust passage opposite to the Stirling engine. This cogeneration system can recover more heat energy from combusted gas.