Abstract: An excitation apparatus for a generator includes an AC/AC inverter having a voltage holding function and connected to an output line of an AC generator. The apparatus includes an AC/DC converter, a capacitor connected to an output of the AC/DC converter, and a DC/AC converter connected to the capacitor and excites a field winding of the generator with an AC/DC converter controllable with a current and connected to the output of the AC/AC inverter. Even when a voltage of the output line is lowered due to a failure in a system, since energy stored in the capacitor is discharged and the voltage is maintained for the time being, the excitation current of the generator can be kept at a sufficiently high value.