To provide a heat exchanger for exhaust air with high corrosion resistance and heat exchange rate, using a tube which is made from a material having durability in contact with liquid and can be inexpensively produced, in which the frequency of tube replacement is reduced, and the necessity of the replacement can be confirmed by a visual method or the like before the replacement is needed, and to provide a heat exchanger for exhaust air, capable of easily performing adjustment of a liquid flow path and a liquid flow rate.

A plurality of parallel stainless tubes are casted in an aluminum sheet body. The sheet body has a thickness of 5 mm or more, and includes a number of truncated conical projections. A number of parallel tubes are divided into two or more tube groups, and a partition constituting a liquid flow path of each tube group is cut out, whereby the liquid flow path can be selected.