PURPOSE: To make the reverse voltage cleaning automatically and simplify the operation remarkably by closing a polarity changeover switch on the reverse voltage cleaning side and opening a flow path selector valve on the drain side by a water supply stop signal when the given electrolytic integrating value is attained and applying the electrolytic voltage of reverse voltage cleaning to an electrolytic power supply circuit by a water supply reopening signal.

CONSTITUTION: An alkali-ionized water preparation device comprises a continuous electrolytic water preparation instrument 1, an electrolytic power supply circuit 2 provided with polarity changeover contact points 19a and 19b for reverse voltage cleaning and a sensing switch 3 for sensing the water supplied to an electrolytic cell 10 and ON/OFF controlling the electrolytic power supply circuit 2. When the given electrolytic integrating value is attained and a water supply signal to the electrolytic cell 10 shows OFF by operating the sensing switch 3, the polarity changeover contact points 19a and 19b of the electrolytic power supply circuit 2 are closed on the reverse voltage cleaning side, and a flow path selector valve 15 of an alkali-ionized water drain piping 12 is opened to the cleaning side, and when the water supply signal to the electrolytic cell 10 issued by the sensing switch 3 shows ON again, the electrolytic voltage for reverse voltage cleaning is applied to the power supply circuit 2 by a control means 4.