A fixing mechanism for use in a peripheral storage device having a cover and a core, includes a first hook slip element on the cover and a second hook slip element on the core. The first hook slip element is formed with a bending part and an extension part. The second hook slip element is formed with a first step part on which the bending part rests and a hook slip part for the extension part to pass therethrough to be engaged with the hook slip part, such that the cover and the core are hooked together in a way that movement of the cover in both vertical and horizontal directions is restricted with respect to the core.