PURPOSE: To improve the temperature efficiency of the heat exchanger by a method wherein the flow path of heat exchanging liquid is provided between laminated flat plates.

CONSTITUTION: A plurality of notches 11 are provided in the surface of the plate and the paths 10 of fluid are provided in the configurations limited by the notches. According to this method, a heat resistance from a high-temperature end in the surface of the plate to the low-temperature end of the same is increased and the flow of heat in the surface is decreased, thereby increasing the temperature efficiency of the plate type heat exchanger.