PURPOSE: To improve the safety of the water heater by a method wherein when an earthquake is sensed, an earthquake-proof safety device is operated to close a water supply pipe and an electromagnetic valve in a drain tube, and when a leak is detected, a leak breaker is operated to stop a control part of a heating device.

CONSTITUTION: The electric water heater 1 of the hot water storing type is connected to the water supply pipe 2 and a hot water supply pipe 3 respectively. Within the electric water heater 1, the electric control part 5 to control the operation of an electric heater is provided and in the lower part of the water heater 1, the drain tube 7 with the electromagnetic valve 10 is arranged. In the above structure, in the water supply pipe 2, the earthquake-proof safety device 4 is provided to interrupt the water supply when an earthquake is sensed. In the electric control part 5, the leak breaker 6 is provided to stop the operation of the electric control part 5 when a leak is detected. When an earthquake is sensed, an earthquake sensing ball 13 is dropped off from a seat 12, which accordingly rises up due to a lifting force of a spring 17, so that the valve 14 is closed to interrupt the water supply to the electric water heater 1. At the same time, an operation lever 15 of a microswitch 16 is operated to cut off the leak breaker 6, while opening the electromagnetic valve 10.