A power supply apparatus for a vehicle supplies/charges electric power to/from a power supply unit. The vehicle includes a first power-inverter circuit, a capacitor, high-resistance and low-resistance electric-paths between the capacitor and a battery, a first switching unit opening/closing the electric-paths, and a unit operating the first switching unit, when connecting between the battery and the first power-inverter circuit, in such a manner that after the high-resistance electric path is closed and the low-resistance electric path is opened, the high-resistance electric-path is opened and the low-resistance electric-path is closed. The apparatus includes an electric power transferring electric-path, an operating unit operating the first power-inverter circuit to supply/receive electric power to/from the power supply unit, and a prohibiting unit prohibiting the electric-path between the power supply unit and the first power-inverter circuit from closing when the amount of charge of the capacitor is equal to or less than a predetermined value.