The present invention relates to a crystal of (2S,4S)-6-fluoro-2,5-dioxospiro[chromane-4,4-imidazolidine]-2-carboxamide, which has more than one characteristic property selected from the group having the following characteristic properties of (a) to (c): (a) an infrared absorption spectral pattern having characteristic absorption bands at around 3507, 3391, 1779, 1727 and 1684 cm-1, (b) a differential scanning calorimetry (DSC) curve having one endothermic peak at a temperature range of 303DEG C ~ 313DEG C, and (c) a powder X-ray diffraction pattern having characteristic peaks at diffraction angles (2&thetas) of 13.1DEG , 13.9DEG , 15.0DEG , 18.2DEG , 23.1DEG and 23.3DEG and the specific optical activity [&alpha]D20 is +170 ~ +173DEG (C = 1.0, methanol).本發明係關於一種(2S,4S)-6-氟-2,5-二側氧螺[苯并二氫吡喃-4,4-咪唑啶]-2-甲醯胺之結晶,其具有選自由下述之(a)~(c)所組成之群中之1種以上之特徵:(a)於3507、3391、1779、1727及1684cm-1附近具有特徵性吸收帶之紅外吸收光譜圖案,(b)於303℃~313℃具有1個吸熱波峰之示差掃描熱量測定(DSC)曲線,以及(c)作為繞射角(2θ),於13.1°、13.9°、15.0°、18.2°、23.1°及23.3°附近具有特徵性波峰之粉末X射線繞射圖案;並且比旋光度[α]D20為+170~+173°(C=1.0、甲醇)。
