An aqueous chlorite solution, an activator for quickly adjusting the pH of the aqueous chlorite solution, an activation inhibitor which causes the action of the activator to be reduced in a delayed manner, and a metal iodide are mixed with 0.4 mass % or less of the metal iodide and 1 mass % or less of the activation inhibitor per 1 L of 1 mass % of the aqueous chlorite solution； from the obtained liquid composition, chlorine dioxide gas is generated immediately and at a stable concentration.將亞氯酸鹽水溶液、快速地調整亞氯酸鹽水溶液的pH之活化劑、徐緩地降低活化劑的作用之活化抑制劑及金屬碘化物，以在1質量%的亞氯酸鹽水溶液每1L中金屬碘化物為0.4質量%以下且活化抑制劑為1質量%以下之比率混合，並從所得到之液性組成物中以即效且穩定的濃度產生二氧化氯氣體。
