A radiator for a liquid cooling type cooling device includes a plurality of fin plates and connecting members integrally connecting all the fin plates. The fin plate includes a vertically elongated rectangular flat plate body and narrow portions integrated with both end portions of the plate body. All the fin plates are arranged at intervals in the thickness direction of the plate body. The connecting member is formed into a corrugated shape and includes flat plate portions each integrated with the narrow portion of the plate body and arcuate portions and each connecting the adjacent flat plate portions. The plate body, the narrow portion, and the flat plate portion are equal in thickness. Both side surfaces of the plate body, both side surfaces of the narrow portion, and both side surfaces of the flat plate portion are positioned on the same plane.