The purpose of the present invention is to provide crystals of a compound that exhibits an analgesic action against neuropathic pain and/or fibromyalgia syndrome, the crystals being useful as pharmaceuticals. The present invention provides crystals of (S)-1-(4-(dimethylamino)piperidin-1-yl)-3-hydroxy-3-(1-methyl-1H-imidazol-2-yl)propan-1-one or a pharmacologically acceptable salt thereof.