A plate type heat exchanger wherein contacting portions of laminated plural plates and fins or contacting portions of laminated plural plates are brazed to form a heat exchange area, characterized in that at least the surface of a plate or fin contacting with a fluid is covered with an alloy comprising in weight ratio 25 35% of chromium, 5 7% of phosphorus, 3 5% of silicon, 0.001 0.1% of at least one selected from the group consisting of aluminum, calcium, yttrium and mischmetal, and balance containing mainly nickel. The alloy may contain 15% or less of iron and or 10% or less of molybdenum.The plate type exchanger exhibits enhanced pressure resistance and is excellent in corrosion resistance.