A plate tube type heat exchanger using porous fins is manufactured of foamed metal. The porous fins used for the plate tube type heat exchanger are formed of a foamed metal such as aluminum or copper having a high thermal conductivity. The plate tube type heat exchanger using such porous fins exhibits an excellent heat transfer capability, compared to a conventional plate tube type heat exchanger using louvered fins, thereby simplifying production steps and realizing an excellent structural rigidity.