In an intake air cooling device, a heat-exchanging core portion in an intercooler has an intake-air downstream-side core portion and an intake-air upstream-side core portion located upstream of the intake-air downstream-side core portion in a flow of intake air. The intake-air downstream-side core portion is located upstream of the intake-air upstream-side core portion in a flow of a cooling fluid. The intercooler has a U-turn portion at which a flow direction of the cooling fluid turns around between the intake-air downstream-side core portion and the intake-air upstream-side core portion. A flow rate control device intermittently supplies the intercooler with a predetermined volume of the cooling fluid at a time. The predetermined volume is a value determined on basis of a volumetric capacity of a cooling fluid channel in the intake-air downstream-side core portion.