A power supply apparatus includes a power source unit configured to supply electric power to an electric load, a capacitor connected to a power supply line extending from the power supply unit to the electric load, a charge circuit configured to charge the capacitor while restricting a current value of the electric power supplied from the power source unit, a specifying unit configured to specify a voltage value of the capacitor, a first determination unit configured to determine whether the charge of the capacitor is completed in accordance with the voltage specified by the specifying unit, and a second determination unit configured to determine whether the voltage specified by the specifying unit is equal to or smaller than an error threshold value after the first determination unit determines that the charge of the capacitor is completed.