The present invention provides an atorvastatin-containing coated preparation comprising a solid formulation containing atorvastatin, a pharmacologically acceptable atorvastatin salt, or a solvate thereof coated with a coating agent comprising a polyvinyl alcohol copolymer, a method for inhibiting generation of related substances of atorvastatin, a pharmacologically acceptable atorvastatin salt, or a solvate thereof, comprising coating the solid formulation with a coating agent comprising a polyvinyl alcohol copolymer, and a method for stabilizing atorvastatin, a pharmacologically acceptable atorvastatin salt, or a solvate thereof.
