A pharmaceutical preparation for remedy of periodontal diseases, which is in the form of a film or sheet and is inserted in a periodontal pocket or gingiva, said pharmaceutical preparation comprising a water-soluble polymeric substance having a Young's modulus of 10 to 250 Kg/mm.sup.2 as determined at a temperature of 25.degree. C. and a relative humidity of 65%, and a viscosity of the 2% aqueous solution of 5 to 30,000 CP as determined at 20.degree. C. and a medicinal agent for remedy of periodontal diseases. This pharmaceutical preparation can be prepared by dissolving the above-mentioned water-soluble polymeric substance and medicinal agent in an organic solvent, casting the resultant solution, and removing the organic solvent by drying to obtain a pharmaceutical preparation in the form of a film or sheet.