An electric power supply of an electric apparatus is provided. The electric power supply includes a low power supply unit configured to convert a voltage of an input alternating current (AC) power source and provide the converted voltage, a power storage unit configured to be charged by receiving the converted voltage from the low power supply unit and to provide the charged power as a standby power of the electric apparatus, a voltage detection unit configured to detect a level of voltage charged in the power storage unit, and a switch unit configured to allow the voltage of the low power supply unit to be supplied to the power storage unit, or to block the voltage of the low power supply unit from being supplied to the power storage unit according to the level of voltage charged in the power storage unit detected through the voltage detection unit.