An object of the present invention is to provide a high-purity aqueous copper sulfonate solution and a simplified method of producing this solution.The aqueous copper sulfonate solution of the present invention is characterized in that the copper concentration therein is at least 90 g/L, the content of metal impurities is less than 10 mg/L as metal for each metal impurity, the content of chlorine is less than 10 mg/L, and the sulfonic acid is a sulfonic acid represented by the following general formula R—(SO3H)n (in the formula, R represents a lower alkyl group, lower alkylidene group, lower alkylene group, or hydroxyalkyl group and n represents 1 or 2).