ObjectProvided are β-form crystal, γ-form crystal, and α-form crystal of a benzoxadiazole derivative, wherein a uniform crystal having sufficient qualities can be obtained with high reproducibility, and they can be anytime supplied as crystals of drug substance for use in producing pharmaceuticals, are particularly suitable for mass synthesis in industrial production, hardly exhibit hygroscopicity and have particularly excellent photo-resistance.Means for ResolutionA solving means includes β-form crystal of 4-[3-isopropyl-5-(6-phenyl-3-pyridyl)-4H-1,2,4-triazol-4-yl]-2,1,3-benzoxadiazole, which shows an endothermic peak at 145 to 150° C. according to a differential scanning calorimeter analysis (DSC analysis) and shows X-ray powder diffraction peaks at 9.8, 11.1, 12.8, 13.3, 17.1, 20.2, 21.2 and 22.3 in 2θ(°), and the like.
