To use an electric water heater for the humidification of a room by performing the humidification of a room by generating a vapor by heating a liquid in a container by a heating means, by a control means, when a user selects or sets at a humidification.

A user fills water in a container 2, and turns on this electric water heater. Then, when a humidifying operation switch 7 is pressed, a control means 6 heats the water by a heater of 925 W of a heating means 5 until a boiling point is detected by a temperature sensor 4. Continuously, the control means 6 keeps feeding power to the heater of 925 W of the heating means 5, and keeps boiling the hot water in the container 2. Then, a vapor is discharged into a room from a vapor port on a lid main body 3. Also, when the humidifying operation switch 7 is pressed during a heat insulation wherein the temperature is regulated by a heater of 75 W of the heating means 5, the control means 6 switches the heater of the heating means 5 from 75 W to 925 W, and the hot water in the container 2 is kept boiling.