In a voltage adjusting apparatus connected in series to a system, an output of an AC/DC converter thereof is reduced. The apparatus includes a second serial transformer having a primary side connected in series to a secondary side of a first serial transformer having a primary side connected in series between a power supply and a load and to a secondary side of a parallel transformer having a primary side connected in parallel between the power supply and the load; and a first AC/DC converter having an AC side connected to a secondary side of the second serial transformer. The first AC/DC converter has a switching element connected between an AC terminal and a DC terminal, an antiparallel diode, and a capacitor.