A hard disk enclosure includes a tray, a cover engaging with the tray, and a case. The tray includes a bezel and a bottom plate. The bottom plate includes a plurality of retainers extending therefrom. The retainers cooperate to form between a space for receiving a hard disk. Each of the retainers forms a protrusion for engaging with the hard disk. The cover includes a rear wall, and an insert wall extending from a side of the rear wall. The case accommodates the bottom plate of the tray and the insert wall of the cover, and is retained between the bezel of the tray and the rear wall of the cover.