PROBLEM TO BE SOLVED: To provide a technique for suppressing color change of an aqueous composition comprising a halogenated isoquinoline derivative during storage at a high temperature.SOLUTION: An aqueous composition comprises: a compound represented by general formula (1) in the figure, a salt thereof or a solvate of them； and a β blocker. [In the formula, X represents a halogen atom.]SELECTED DRAWING: None【課題】ハロゲン化イソキノリン誘導体含有水性組成物の、高温保存時の変色を抑制する技術の提供。【解決手段】次の一般式（１）［式中、Ｘはハロゲン原子を示す。］で表される化合物若しくはその塩又はそれらの溶媒和物、及びβ遮断薬を含有する、水性組成物。【選択図】なし
