Disclosed is a preparation which, in an orally fast-disintegrating tablet having as an active ingredient 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid, causes basically no irritation in the mouth or throat, retains good dissolvability and oral disintegration even when stored under high temperature or high humidity conditions. The disclosed orally fast-disintegrating tablet is formed to contain particles comprising nuclear particles which contain 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid, which are covered by a layer containing a methacrylic acid copolymer, and which are further coated with an outer layer containing water-soluble sugars, such that after two weeks of storage under conditions with the cap open at 40C / 75% RH, a dissolution test performed according to the Japanese Pharmacopoeia Paddle Method at 50 revolutions per minute (test solution: pH6.0McIlvaine buffer) evaluates the dissolution rate of the 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid at 70% or greater after 10 minutes.
