PROBLEM TO BE SOLVED: To provide a novel method for producing chlorous acid water capable of stably maintaining chlorous acid in water for a long time. SOLUTION: Chlorine dioxide gas (ClO2) is trapped (trap, trapped or adsorbed) in an inorganic acid, an inorganic acid salt, an organic acid or an organic acid salt, or in a combination of two or more kinds or a combination thereof. A method of maintaining chlorous acid (HClO2) in water stably for a long time by creating a transition state by delaying the decomposition reaction. For example, the gas cleaning device 2 is filled with H2O, NaOH, H2O2 as a gas cleaning liquid, chlorine dioxide gas is prepared in the chlorine dioxide gas storage tank 3, and sodium carbonate and dipotassium hydrogen phosphate are stored in the chlorite water production tank 1. 4. A method of producing chlorite water by filling sodium tetraborate, operating the air pump 4, and causing chlorine dichloride to flow into the chlorite water production tank 1. [Selection diagram] 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に二酸化塩素ガスが準備され、亜塩素酸水製造タンク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タンク１に二塩化塩素を流入させ、亜塩素酸水を製造する方法。【選択図】図１
