To provide a new exhaust heat recovery device for recovering sensible heat in exhaust gas discharged from a furnace or an internal combustion engine as fuel, such as an H2 fuel.

A heat exchanger, where a catalyst for reforming DME is filled, is installed in the exhaust system of a combustion apparatus, such as a furnace, an internal combustion engine, and a generator set. By passing the mixed gas of DME and H2O to the heat exchanger, DME is thermally decomposed and sensible heat in the exhaust gas of the furnace or the internal combustion engine is recovered as the H2 fuel. The exhaust heat is not recovered simply as vapor, hot water, heated air, or the like but is recovered as the H2 fuel, or H2 and a CO fuel, so that the applications of the recovered energy are not limited (namely, it is recovered as the combustion heat of fuel, thus preventing the recovered energy from decreasing even if the energy is transported to a distant place).