The present invention relates to an oral pharmaceutical preparation having an excellent capability of delivering a drug to colon, more specifically an oral pharmaceutical preparation for delivering a drug to colon and comprising a core comprising at least a pharmaceutically acceptable vehicle, an inner layer covering said core and comprising said drug, an intermediate layer covering said inner layer and comprising a cationic polymer soluble or swellable at a pH of not more than 6.6, and an outer layer covering said intermediate layer and comprising an anionic polymer soluble at a pH of not less than 7.0.
