First passages of a heat exchanger each include a plurality of channels that each connect an inlet formed in an inflow surface of a core and an outlet formed in an outflow surface of the core together. The channels have different channel resistances. The heat exchanger includes a flow-directing member of a first type disposed to a side of the core where the inflow surface is located to provide a uniform distribution of a dynamic pressure of the first fluid flowing into the core to the inflow surface; and a flow-directing member of a second type reducing a difference between flow rates of the first fluid through the channels arising from a difference in channel resistance between the channels forming each first passage of the core.
