PURPOSE: To electrically adjust mixed hot water temperature without using a commercial electric power source.

CONSTITUTION: A mixing valve 19 to adjust a mixing ratio of hot water and cold water is driven by a mixing valve motor 23, mixed hot water temperature is feedback controlled by way of detecting it by a thermistor 25, supply-stop of mixed hot water is carried out by a flow rate control valve 27 by way of setting a setter 31, and at the time of stopping mixed hot water, driving of the mixing valve motor 23 is stopped and simultaneously the mixing vale motor 23, the setter 31 and a controller 32 are electrified by a battery 34.