PURPOSE:To accurately and instantly adjust the temperature of delivery hot water by a structure wherein a diaphragm valve, which is actuated by the outputs of a plurality of hot water outflowing paths, is arranged in a by-pass passaage so as to automatically change-over the flow path in response to the running of water in the outflowing path. CONSTITUTION:An outflowing path 8 branches off so as to connect to a nozzle 10 for washing the anus and to a nozzle 11 for the bidet and solenoid valves 12 and 13 are respectively arranged in flow paths led to said nozzles 10 and 11. A NOR type diaphragm valve 15, which is actuated by the pressure on the downstream sides of the solenoid valves 12 and 13, is inserted in a by-pass passage 14 communicating from the upstream side of the solenoid valves 12 and 13 in the outflowing path 8 to the suction side of a water pump 9. A control unit 18 controls the input to a heat generating body 21 based upon the outputs of the hot water temperature sensor 19 of a hot water storage chamber and of a delivery hot water temperature sensor 20 and the operation of the water pump 9. The operation is made simpler and the action surer, because the pressure of slip streams generated by turning ON of the solenoid valves (or of the on-off valves in the outflowing paths) are used.