The present invention provides polymyxin B sulfate crystals and a method for producing the same. The production method of the present invention comprises a step of adsorbing a polymyxin B fermentation solution to a resin and desorbing it by adding sulfuric acid or acidic ethanol； a step of concentrating to obtain a saturated solution of polymyxin B sulfate； and an organic solvent. Using to precipitate crystals from the saturated solution, followed by filtration and drying to obtain polymyxin B sulfate crystals. [Selection] Figure 1A【課題】本発明はポリミキシンＢ硫酸塩結晶及びその製造方法を提供する。【解決手段】本発明の製造方法は、ポリミキシンＢ発酵液を樹脂に吸着させ、硫酸又は酸性エタノールを添加して脱着させる工程；濃縮してポリミキシンＢ硫酸塩飽和溶液を得る工程；並びに有機溶媒を用いて該飽和溶液から結晶を沈殿させ、ろ過及び乾燥を行って、ポリミキシンＢ硫酸塩結晶を得る工程を含む。【選択図】図１Ａ
