A heat sink unit comprising a substrate, a fan, driving means, a fin composed as a separate body from the substrate, and a cover. The cover has a first opening in a section facing the fan, and also forms a second opening with the substrate at one side of the cover. The fin is composed of a separate material from the substrate, and fixed to an opening provided in the substrate. A height from a bottom surface of a heat sink substrate to an upper surface of a cover at a section the fin is disposed is larger than that at a section where the fan is disposed. A thickness of a base of the fin is larger than a thickness of the heat sink substrate. Furthermore, an electronic apparatus of this invention has a heat sink unit of this invention disposed within the apparatus.