This method for producing a potassium perfluoroalkanesulfonate includes an electrochemical fluorination step in which an alkanesulfonyl halide compound is subjected to electrochemical fluorination in anhydrous hydrogen fluoride, thereby to generate a production gas containing perfluoroalkanesulfonyl fluoride as the main component. In addition, for example, the methods may include a gas absorption step in which the production gas is reacted with an aqueous solution of potassium hydroxide, thereby to generate a gas absorbed solution containing potassium perfluoroalkanesulfonate, a purification step in which impurities such as potassium fluoride, potassium hydroxide, and potassium sulfate, are removed, and a concentration and collection step in which the aqueous solution from which the impurities are removed is concentrated and dried. In the electrochemical fluorination, for example, it is possible that the proton concentration in the reaction solution is maintained in the range of 150 to 1,500 ppm to suppress the formation of byproducts.