An apparatus and method for supplying power to an electronic device are provided. The apparatus includes a power converter, a main converter, and a sub converter. The power converts includes a rectifier configured to convert alternating current (AC) power into direct current (DC) power, and a smoothing condenser connected to an output terminal of the rectifier. The main converter is connected with an output terminal of the power converter and configured to supply power to a first component of the electronic device. The sub converter is connected with the output terminal of the power converter, and configured to supply power to components other than the first component, and to stop supplying the power in response to a momentary power interruption or a voltage dip occurring in the AC power.