PROBLEM TO BE SOLVED: To provide: a (8S,9R)-5-fluoro-8-(4-fluorophenyl)-9-(1-methyl-1H-1,2,4-triazol-5-yl)-8,9-dihydro-2H-pyrido[4,3,2-de]phthalazin-3(7H)-one tosylate salt including a crystalline form, which is compound effective for treatment of cancer； and a method for preparing the same.SOLUTION: There is provided a method for preparing a composition which comprises the following steps: a step (1) of contacting a free base of the compound with p-toluenesulfonic acid at a high temperature in the presence one or more solvents independently selected from THF, acetone, methanol, acetonitrile and DCM ； a step (2) of allowing the base to be left under conditions sufficient to precipitate the crystalline form； and a step (3) of isolating the crystalline form.SELECTED DRAWING: None【課題】癌の治療に有効な化合物である、結晶性形態を含む、(8S,9R)-5-フルオロ-8-(4-フルオロフェニル)-9-(1-メチル-1H-1,2,4-トリアゾール-5-イル)-8,9-ジヒドロ-2H-ピリド[4,3,2-de]フタラジン-3(7H)-オントシレート塩形態、及びその調製方法の提供。【解決手段】下記工程（１）～（３）を含む組成物の調整方法。工程(1):THF、アセトン、メタノール、アセトニトリル、及びDCMから独立に選択される1以上の工程1の溶媒の存在下、高温で、前記化合物の遊離塩基をp-トルエンスルホン酸と接触させること；工程(2):該結晶性形態を沈殿させるのに十分な条件下で静置させておくこと；並びに工程(3):該結晶性形態を単離する【選択図】なし
