A controlled release pharmaceutical composition containing (1) (R)-2-(2-aminothiazol-4-yl)-4'-[2-[(2-hydroxy-2-phenylethyl)amino]ethyl]acetic acid anilide or a pharmaceutically acceptable salt thereof, (2) one or more additives for having water seep into the inside of the preparation, said additives having such a solubility that the amount of water required for dissolving 1g of the additives is not more than 10 mL, and (3) a polymer material for forming a hydrogel, said polymer material having an average molecular weight of about 100,000 or more and a viscosity of not less than 12 mPa·s as measured in the form of a 5% aqueous solution at 25˚C.
