To realize a flat heat exchanger with superior stability of the flow path, a heat exchanger for liquid cooling in which a cooling liquid flows inside the heat exchanger includes a pouch made of a water-resistant sheet having an inflow port and an outflow port for the cooling liquid; a heat exchange plate overlapping with the pouch; a presser plate pressing the pouch against the heat exchange plate; wherein protrusions and depressions delimiting a flow path linking the inflow port and the outflow port are formed on the inner side of at least one of the heat exchange plate and the presser plate.