[Document Name] Abstract[Abstract]Disclosed is a process for producing A-form crystals of2-(3-cyano-4-isobutyloxypheny0-4-methyl-5-thiazolecarboxylic acid, comprising: a step of dissolving by heating 2-(3-cyano-4-isobutyloxyphenyI)-4-methyl-5-thiazolecarboxylic acid in one or a plurality of solvents as a good solvent, selected from the group consisting of 1-propanol, 2-propanol, ethanol, and acetone； a step of cooling the solution； and a step of adding to the solution a hydrocarbon solvent as a poor solvent.
