A plate heat exchanger causes heat exchange to be performed using a plurality of heat transfer plates stacked. Each of the heat transfer plates includes a plate body, a first-medium inlet, a first-medium outlet, a second-medium inlet, a second-medium outlet, and a projection that provides a passage. At least one of the first-medium inlet and the first-medium outlet is located at one of two corners at one end of the plate body which the projection contacts. At least one of the second-medium inlet and the second-medium outlet is located at one of two corners at the other end of the plate body from which the projection is separated.