PURPOSE: To compensate washing insufficiency in the case washing is stopped on the way, and to prevent deterioration of the electrolytic capacity by restarting the electrolysis in the course of automatic washing of an ion water generator.

CONSTITUTION: When electrolysis is finished, a control circuit 6 sends out a cleaning signal, and as soon as a polarity inversion relay is switched and washing is started, a washing time counter 3 inputs a clock through a NAND circuit 5, and starts a decrement of a set washing time. When the electrolysis is restarted by supplying water in the course of washing operation, and washing is stopped, the eashing time counter 3 stores the remaining time, and after the electrolysis is finished, a control circuit sends out the washing signal and executes washing until a count value becomes zero by a decrement of the remaining time.