PROBLEM TO BE SOLVED: To provide a manufacturing method of high purity and high yield tolvaptan, a salt thereof, or a solvate thereof without using a solvent with large environmental load, and having enhanced operability of a reaction.SOLUTION: There is provided a manufacturing method of tolvaptan, a salt thereof, or a solvate thereof, including a process for reacting following a described carboxylic acid derivative (I) with a chlorination agent such as thionyl chloride to convert it to a corresponding acid chloride (I), in which the reaction process is conducted in a presence of a solvent having relative dielectric constant of 10 or more and donor number of 20 or more, and represented by N,N-dimethyl acetamide, N-methyl-2-pyrrolidone, N.N'-dimethyl propylene urea or N,N,N',N'-tetramethyl urea.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】環境負荷が大きい溶媒を用いず、反応の操作性が向上され、かつ、高純度、高収率なトルバプタン、その塩、又はそれらの溶媒和物の製造方法の提供。【解決手段】下記カルボン酸誘導体（Ｉ）を塩化チオニル等のクロロ化剤と反応させて対応する酸塩化物（ＩＩ）に変換する工程を含むトルバプタン、その塩、又はそれらの溶媒和物の製造方法であって、前記反応工程が、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ－メチル－２－ピロリドン、Ｎ，Ｎ’－ジメチルプロピレン尿素又はＮ，Ｎ，Ｎ’，Ｎ’－テトラメチル尿素に代表される、比誘電率が１０以上であり、かつ、ドナー数が２０以上である溶媒の存在下で行われる前記製造方法。【選択図】なし
