Abstract: An electrolytic cell for producing acidic water and alkaline water is disclosed. High-purity acidic water and high-purity alkaline water can be produced in a well balanced proportion from ultrapure water which is supplied in the minimum amount necessary for producing the desired acidic and alkaline waters using the minimum amount of electricity. The electrolytic cell includes an electrolytic acidic-water production unit 3 comprising an anode chamber 6 and an auxiliary cathode chamber 7 separated therefrom by a first ion-exchange membrane 5, and an electrolytic alkaline-water production unit 4 comprising a cathode chamber 10 and an auxiliary anode chamber 9 separated therefrom by a second ion-exchange membrane 8. Separately controllable power supplies are also provided for supplying power to each of the two units. The supply amount of pure water and the amount of electricity used can be fixed according to the desired amounts of acidic and alkaline waters.