Disclosed is a controlled release nucleated tablet which is composed of an inner nucleus and an outer layer that covers the inner nucleus and is capable of maintaining the level of 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5- thiazolecarboxylic acid in the blood to a certain value or higher for a long period of time. The controlled release nucleated tablet is characterized in that the inner nucleus contains 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5- thiazolecarboxylic acid and the outer layer contains 2-(3-cyano- 4-isobutyloxyphenyl)-4-methyl-5-thiazolecarboxylic acid and a gel-forming water-soluble polymer that is in an amount of 16 (w/w)% or more relative to the weight of the outer layer.
