A Plate and Shell type plate heat exchanger, which comprises an inner shell (9) completely surrounding a plate pack (2) and inner end plates (11a, 11b) in the direction of the ends of the plate pack. The inner shell (9) is by its inner surface arranged into contact with the outer edge of the baffle plates (8a, 8b) arranged on the surface of the plate pack and by its outer surface the inner shell (9) is arranged to support itself against the inner surface of the shell (3) of the outer casing of the heat exchanger. The inner end plates (11a, 11b) are supported by their outer surface against the inner surface of the end plates (4a, 4b) of the outer casing.