PURPOSE: To display a remaining time until water is boiled accurately, regardless of the water quantity, at the time of heating to boil operation of a water boiling device.

CONSTITUTION: When power connection is started by a heater 3, a triangle- shaped first display part 11 is lit up, and when a detected temperature has reached 5O°C, a second display part 12 is lit up, and when the detected temperature has reached 75°C, a third display part 13 is lit up, and thus, the ascent of water temperature is displayed with time. When the detected temperature has reached 90°C, a remaining time until the water is boiled is set, based on the detected temperature ascending rate up to that time and remaining time data which is stored in a memory means 21, and the remaining time is displayed by figures on a remaining time display part 14, and the remaining time is countdown-displayed at each specified period of time. By this method, an accurate remaining time until the water is boiled can be recognized.