To automatically control appropriate water supply and discharge time regardless of the amount of water to be supplied and discharged.

A control means 23 is controlled by signals from a water supply detection electrode 5 and a remaining water detection electrode 14 and performs appropriate power supply by supplying the water until the signals for indicating that no more water is present in a main body power supply part 2 are detected by the power supply detection electrode 5. Also, at the time of discharging water, an appropriate water discharge operation is performed by discharging the water until the signals for indicating that no more remaining water is present are detected in a remaining water detection means 4 and useless water discharge operation time is not taken.