This aqueous chlorine dioxide solution contains chlorine dioxide, a potassium salt of a weak acid having a pKa of 2.5 or more, and a chlorite, while having a pH of from 4.0 to 7.5 (inclusive). A method for producing an aqueous chlorine dioxide solution according to the present invention comprises: a first step for preparing a first aqueous solution that contains chlorine dioxide； a second step for preparing an intermediate aqueous solution having a pH of from 4.0 to 7.5 (inclusive) by mixing the first aqueous solution with a second aqueous solution that contains a potassium salt of a weak acid having a pKa of 2.5 or more； and a third step for preparing an aqueous chlorine dioxide solution having a pH of from 4.0 to 7.5 (inclusive) by mixing the intermediate aqueous solution with a third aqueous solution that contains chlorite, or alternatively by mixing the intermediate aqueous solution with the third aqueous solution and subsequently adding the second aqueous solution thereto. Consequently, the present invention provides: an aqueous chlorine dioxide solution wherein the concentration of chlorine dioxide is stably maintained without using a phosphate or a salt thereof as a pH adjusting agent； and a method for producing this aqueous chlorine dioxide solution.二氧化氯水溶液包含二氧化氯、pKa為2.5以上的弱酸的鉀鹽及亞氯酸鹽，pH為4.0以上且7.5以下。二氧化氯水溶液的製造方法包括：第一步驟，準備包含二氧化氯的第一水溶液；第二步驟，藉由將第一水溶液與包含pKa為2.5以上的弱酸的鉀鹽的第二水溶液混合，製備pH為4.0以上且7.5以下的中間水溶液；以及第三步驟，藉由將中間水溶液與包含亞氯酸鹽的第三水溶液混合，或者藉由在將中間水溶液與第三水溶液混合後進而添加第二水溶液，製備pH為4.0以上且7.5以下的二氧化氯水溶液。藉由該些，提供一種不使用磷酸鹽或其鹽作為pH調整劑而穩定地維持二氧化氯的濃度的二氧化氯水溶液及其製造方法。
