An enclosure includes a housing, partition plates received in the housing, hard disk drives fixed between the partition plates, a cover fixed to the housing, a printed circuit board received in the housing and a fan assembly fixed within the housing. The housing includes a bottom plate and a pair of side plates. Each side plate has a guiding device mounted thereon. The guiding device includes a supporting element fixed to the side plate, a fixing element fixed with the printed circuit board, and a rod pivotably connecting the fixing element with the supporting element. The partition plates each have a hook, and the printed circuit board defines multiple slots corresponding to the hooks. The printed circuit board can be driven towards the partition plates by the fixing element around the supporting element so that the slots are aligned and locked with the hooks.