PURPOSE: To improve the electrolytic efficiency of an ionized water forming device by setting the electrolytic level applied accross the second anode present between a first anode and the diaphragm and the second cathode present between a first cathode and the diaphragm so as to make the same equal to or higher than the electrolytic level applied across the first anode and the first cathode to alternately output the electrolytic levels of two systems.

CONSTITUTION: An anode A2 is disposed between an adode A1 and a diaphragm and a cathode C2 is disposed between a cathode Cl and the diaphragm. The electrolytic level applied across the anode A2 and the cathode C2 is set so as to be equal to or slightly higher than the electrolytic level applied across the anode A1 and the cathode C1. A control part 3 controls the application timings of the electrolytic levels of these two systems on the basis of the timings of the electrolytic levels alternately applied across the anode A1 and the cathode C1 and across the anode A2 and the cathode C2. Or, the outputs of the electrolytic levels of two systems are controlled in a partially superposed state. By this method, electrolytic efficiency is enhanced.