To provide a highly efficient evaporation type heat exchanger.

Front and rear end face plates 2, a plurality of heat transfer pipes 3, and a plurality of evaporating radiation pieces where the surface of a metal radiation piece 4 is covered with a hygroscopic material 5 and then is machined and formed are combined, the evaporating radiation pieces are overlapped in layers, the heat transfer pipes 3 closely joined to the evaporating radiation pieces through the evaporating radiation pieces, cooling water in a machine body is drawn and is make to adhere to the hydroscopic material 5, and heat in the heat transfer pipe 3 is absorbed by the adhering cooling water for evaporation, thus decreasing the working pressure and temperature of a substance to be cooled and improving heat exchange efficiency.