There is provided a power supply apparatus which is easy in attempting to unify the thickness distribution of a thin film to be formed on the surface of a substrate even at the time of charging pulsed potential at a low frequency to targets that make respective pairs. The power supply apparatus of this invention has: a first discharge circuit which alternately charges predetermined potential to a pair of targets that are in contact with a plasma at a predetermined frequency; and a second discharge circuit which charges predetermined potential between the ground and the target, out of the pair of targets, that is not receiving output from the first discharge circuit.