PROBLEM TO BE SOLVED: To provide a technique to inhibit the discoloration of a halogenated isoquinoline derivative-containing aqueous composition during high-temperature storage.SOLUTION: The present invention provides an aqueous composition comprising a compound represented by the general formula (1) [where X represents a halogen atom] or a salt thereof or a solvate thereof, and mannitol.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、及びマンニトールを含有する、水性組成物。【選択図】なし
