A highly stable crystal of (1S)-1,5-anhydro-1-[5-(4-{(1E)-4-[(1-{[2-(dimethylamino)ethyl]amino}-2-methyl-1-oxopropan-2-yl)amino]-3,3-dimethyl-4-oxobut-1-en-1-yl}benzyl)-2-methoxy-4-(propan-2-yl)phenyl]-D-glucitol, and a process for producing the crystal are provided. Specifically, an ethanolate having the following physical properties, and a plurality of other crystal forms transformed from the ethanolate are provided: (a) Having peaks at. 2¸ = 5.9 degrees, 17.1 degrees, 17.6 degrees and 21.5 degrees in X-ray powder diffraction (Cu-K±) (b) Showing characteristic absorption bands at 3538 cm -1 , 3357 cm -1 , 2964 cm -1 , 1673 cm -1 , 1634 cm -1 and 1505 cm -1 in an infrared absorption spectrum and (c) Having a melting point in a vicinity of 111°C.본 발명은 (1S)-1,5-안히드로-1-[5-(4-{(1E)-4-[(1-{[2-(디메틸아미노)에틸]아미노}-2-메틸-1-옥소프로판-2-일)아미노]-3,3-디메틸-4-옥소부트-1-엔-1-일}벤질)-2-메톡시-4-(프로판-2-일)페닐]-D-글루시톨에 대해서, 안정성이 높은 결정 및 그의 제조 방법을 제공한다. 구체적으로는, 이하의 물성을 갖는 에탄올 용매화물과, 에탄올 용매화물로부터 변동된 다른 복수의 결정형이다 (a) 분말 X선 회절(Cu-Kα)로, 2θ=5.9도, 17.1도, 17.6도 및 21.5도에 피크를 갖는다 (b) 적외 흡수 스펙트럼에 있어서, 특성 흡수대가 3538 cm-1, 3357 cm-1, 2964 cm-1, 1673 cm-1, 1634 cm-1 및 1505 cm-1에 있다 및 (c) 융점이 111℃ 부근이다.
