To provide novel crystals useful as an ingredient for the production of a diabetes remedy. The invention is concerned with α-form crystal and β-form crystal of (R)-2-(2-aminothiazol-4-yl)-4-[2-[(2-hydroxy-2-phenylethyl)amino]ethyl]acetanilide. The α-form crystal does not exhibit hygroscopicity and has stability such that it can be used as a medicine, and is useful for mass synthesis in the industrial production. The β-form crystal does not relatively exhibit hygroscopicity and is also useful as a production intermediate of the α-form crystal.
