To provide a heat exchanger with a small number of parts in which a heat radiating fin for transmitting heat to a cooling fluid is prepared on a base plate with a heat generating part thermally connected and an excellent heat radiation effect is exhibited by controlling the flow of the cooling fluid, and to provide a means for reducing parts cost and, as a result, joining work cost.

The heat exchanger is structured such that it uses a fin 10 with louvers as a heat radiating fin to induce a flow of a cooling fluid by preparing fluid inducing means 17 and 18 on the base plate for guiding the flow of the cooling fluid flowing in from an entry 15 to an in-plane parallel with a plate surface of the base plate and guiding the cooling fluid from the entry to the fin with the louvers so that the cooling fluid may almost equally pass through a number of air gaps among respective louvers 12 cut and bent in the fin with louvers and reach an exit 16.