A water healer including a controller that, in a non-operation state, determines whether the first operation was made after a power source is switched on in S1, and determines whether 5 minutes has passed after finishing the last operation in S2. When the first operation was not made or 5 minutes have lapsed after the last operation, the controller determines whether a difference between a detected temperature acquired by a thermistor and a preset temperature is more than 10° C. in S3. When a temperature difference is more than 10° C., a water flow rate servo is made to stand by at a position with a flow rate of flowing water reduced to less than a determined flow rate by a predetermined amount in S4. When a hot water faucet is opened in this standing by state, a temperature control of discharged hot water at the time of starting of an operation is performed with the reduced flow rate of flowing water.