PLATE HEAT EXCHANGER

To provide a plate heat exchanger free from degradation of gaskets which form a flow path through which a high-temperature fluid flows. In the plate heat exchanger, a plurality of heat transfer plates 20 each provided with passage holes 21, 22, 23, and 24 in corners are stacked; a flow-path forming gasket 31 is interposed between peripheries of each adjacent ones of the heat transfer plates 20; communicating-path forming gaskets 32 are installed, surrounding the passage holes 21 in each adjacent ones of the heat transfer plates 20 alternately; and thereby a first flow path 1 adapted to pass a high-temperature fluid H, a second flow path adapted to pass a low-temperature fluid C, and communicating paths 3 adapted to cause the high-temperature fluid H and the low-temperature fluid C, respectively, to flow in and out of the first flow path 1 and the second flow path 2 are formed alternately on opposite sides of each of the heat transfer plates 20. The flow-path forming gasket 31 is made up of an inner gasket member 31a and an outer gasket member 31b arranged in two parallel lines.