Provided is a plate heat exchanger that includes a plurality of heat transfer plates stacked to each other, a gasket interposed between each adjacent heat transfer plates, and a regulating member formed to be able to support at least partially the gasket. Each heat transfer plate has a fitting recessed portion formed in recessed manner on the side on which the gasket fitting groove is formed. The fitting recessed portion crosses the recessed strip while extending along the gasket fitting groove. The support part is arranged along the gasket fitting groove when the regulating member is held in fitting engagement with the fitting recessed portion. The support part is arranged along the gasket fitting groove when the regulating member is held in fitting engagement with the fitting recessed portion.