An adhesion of a preparation 1 to an inner wall of an oral cavity is prevented by applying an anti-adhesive composition containing a water-soluble cellulose ether (e.g., an HPMC) and an anionic polymer (e.g., a carboxyvinyl polymer) to a gel-forming layer 4 covering a drug-containing unit 2 to form an anti-adhesive layer 5. The gel-forming layer 4 may be formed with a gel-forming agent (a carboxyvinyl polymer), a crosslinking agent, and a base material (e.g., a poly(vinyl alcohol)). An adhesive layer 3 may be interposed between the drug-containing unit 2 and the gel-forming layer 4.