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.
