According to the present invention, a hot water heater comprises: a control box including a controller; a heater rod composed of a heating unit; an electrode tube connected to the control box and arranged between a pair of metal tubes; a temperature sensor for reset attached to either one of the one pair of metal tubes and located between an end portion of the electrode tube and the heating unit; and a connection electrode electrically insulated from the electrode tube to be connected to each other. Therefore, the hot water heater prevents corrosion of the electrode tube and the metal tubes underwater and minimizes consumption currents.
