Provided is a power supply apparatus with low power in a standby mode. The apparatus includes a voltage multiplier configured to multiply an input voltage and including a first terminal through which the multiplied voltage is output and a second terminal through which a voltage lower than a voltage of the first terminal is output; a main switch-mode power supply (SMPS) configured to receive the voltage of the first terminal of the voltage multiplier; and a standby SMPS configured to receive a voltage of the second terminal of the voltage multiplier.