Provided are: a coated preparation which cannot be dissolved in the stomach but can be dissolved in the intestine to ensure a coated active ingredient to reach the intestine, and can be prevented expeditiously from being deteriorated over time, and has excellent storage stability； and a method for producing the coated preparation. A coated preparation comprising: a substance to be coated； an under layer which is formed on the substance and contains a polymeric compound (A) having such a property that an aqueous 6 mass% solution has a viscosity of less than 300 mPas at 25 DEG C； and an enteric coating layer which is formed on the under layer and contains an alginate salt (B) and a plasticizer (C).本發明係提供在胃中不溶而在腸中溶解，不僅可使經包覆之有效成分更確實地到達至腸，並能夠盡可能地抑制經時劣化，保存安定性亦優異的包衣製劑及其製造方法。一種包衣製劑，其特徵為具有被包覆物、在其上所形成之下層及在該下層上所形成之腸溶性包覆層；該下層包含(A)6質量%水溶液之於25℃之黏度係未滿300mPa．s的高分子化合物；該腸溶性包覆層包含(B)海藻酸鹽及(C)可塑劑。
