Provided is a prefabricated shelf which can be used to display or store various products or items in a shop or a warehouse, and may include, but is not limited to, vertical frame, a horizontal frame and a shelf panel. A horizontal frame having an engaging slot is engaged to the vertical frame having a plurality of engaging protrusions in a predetermined arrangement, thus easily and durably assembling a shelf without using a separate engaging member, for example, a screw, a bolt, etc., and if necessary it is possible to freely adjust the height of a shelf crosspiece of the vertical frame.