A cooler of the present invention is provided with a case having a top plate, a bottom plate, and a side plate, cooling fins disposed inside the case, and a flow path for cooling fluid that comes into contact with the cooling fins and that flows through the interior of the case, the cooler cooling an object to be cooled in contact with the top plate or the bottom plate. The cooling fins have a shaft part and vane parts that protrude outward from the shaft part and extend spirally in the axial direction; the overall cooling fin configuration constituting a quadrangular column shape. The cooling fins are disposed in contact with at least the top plate and the bottom plate, and the flow path has a spiral-formed configuration formed by the vane parts, the top plate, and the bottom plate.