In a voltage adjusting apparatus connected in series to a system, an output of an AC/DC converter thereof is reduced.Provided are: a second serial transformer 21 having a primary side connected in series to a secondary side of a first serial transformer 13 having a primary side connected in series to the system and to a secondary side of a parallel transformer 14 having a primary side connected in parallel to the system; and a first AC/DC converter 22 having an AC side connected to a secondary side of the second serial transformer 21. The first AC/DC converter 22 has a switching element 22c connected between an AC terminal 22a and a DC terminal 22b, an antiparallel diode 22d, and a capacitor 22e.