To surely prevent a hook of a rail from coming off an attachment hole and the rail from falling off and also enhance efficiency of the work for installation of the rail and change of height position.

A plurality of attachment holes are made in a vertical arrangement in a storage chamber, and the rail has hooks to be freely detachably fitted in the attachment holes and is attached freely detachably by using this attachment hole. A shelf is placed on the rail. The rail constitutes a topside part, a mounting part, and a placing part, and the above mounting part is equipped vertically with the above hooks which are to be locked in the above attachment holes on its top and bottom faces.