A casing device is provided in this disclosure. The casing device comprises a casing body and a slide rail assembly. The casing body includes a side panel and a top bracket. The slide rail assembly is movably arranged on the casing body. The slide rail assembly includes a slide component and a slide rail. The slide component is fixed with the slide rail. When the slide rail assembly is in a first position, the side panel is fastened to the top bracket and the slide rail. When the slide rail assembly moves from the first position to a second position, the side panel is able to be detached from the top bracket and the slide rail.