To provide a hot water heater with high energy efficiency and with the number of parts reduced by eliminating a prior art electromechanical Thermostat, to which water heater protection of drying red heat is applied.

In one mode of the present water heater 10, there are provided a water container 16, an element 26 disposed for heating water in the water container 16, a sensor disposed to detect temperature in the vicinity of the element 26, and a control device connected with the element 26 and the sensor and being capable of disconnecting the element 26 when a plurality of temperatures are compared with each other, and a difference between the plurality of the detected temperatures for a predetermined time is larger than a previously determined temperature. In another mode, there are provided the water container 16, the element 26, a sensor disposed to detect temperature of water in the water container 16, and a control device connected with the element 26 and the sensor and being capable of energizing the element based upon comparison between temperature information received from the sensor and the previously determined temperature.