PROBLEM TO BE SOLVED: To provide a novel method for producing aqueous chlorous acid capable of stably maintaining chlorous acid in water for a long time.SOLUTION: There is provided a method for stably maintaining chlorous acid (HClO) for a long time by generating a transition state by trapping (capturing or absorbing) chlorine dioxide gas (ClO) with a single substance of inorganic acid, inorganic acid salt, organic acid or organic acid salt, two or more single substances or a combination thereof and delaying a decomposition reaction. There is provided a method for producing aqueous chlorous acid by filling HO, NaOH, and HOin a gas cleaning device as a gas cleaning liquid, preparing chlorine oxide gas in a chlorine oxide gas storage tank 3, filling sodium carbonate, dipotassium hydrogenphosphate and sodium tetraborate and the gas cleaning liquid in an aqueous chlorous acid production device 1 and flowing carbon dichloride into the aqueous chlorous acid production device 1 by operating an air pump 4.SELECTED DRAWING: Figure 1【課題】長時間にわたって水中で亜塩素酸を安定して維持できる亜塩素酸水の新規製造方法の提供。【解決手段】二酸化塩素ガス（ＣｌＯ２）を無機酸、無機酸塩、有機酸又は有機酸塩をいずれか単体、または２種類以上の単体もしくはこれらを併用したものにトラップ（ｔｒａｐ、捕捉ないし吸着）させることによって、遷移状態を作り出し、分解反応を遅らせることで長時間にわたって亜塩素酸（ＨＣｌＯ２）を水に安定して維持する方法。例えば、ガス洗浄装置２にガス洗浄液としてＨ２Ｏ、ＮａＯＨ、Ｈ２Ｏ２が充填され、二酸化塩素ガス貯蔵タンク３に酸化塩素ガスが準備され、亜塩素酸水製造装置１に、炭酸ナトリウム、リン酸水素二カリウム、４ホウ酸ナトリウムと前記ガス洗浄液の成分が充填され、エアーポンプ４を稼働させて亜塩素酸水製造装置１に二塩化炭素を流入させ、亜塩素酸水を製造する方法。【選択図】図１
