A heat recovery device, including a pillar-shaped honeycomb structure comprising an outer peripheral side wall having one or more planar outer peripheral side surfaces; one or more thermoelectric conversion modules arranged to face the one or more planar outer peripheral side surfaces; a tubular member that circumferentially covers the outer peripheral side surfaces of the honeycomb structure and the one or more thermoelectric conversion modules; and a casing that circumferentially covers the tubular member; wherein the partition walls are mainly configured of ceramics; and wherein the casing has an inflow port and an outflow port for a second fluid having a temperature lower than that of the first fluid, and a flow path for the second fluid is formed circumferentially around the tubular member between an inner surface of the casing and an outer surface of the tubular member.