An amplitude of current ripples on a primary side of a power supply device that uses a plurality of transformers is reduced. A driving power supply device (7) that supplies electric power to a plurality of drive circuits (2) that individually drive switching elements (3) of an inverter (10) includes a plurality of transformers (L) having secondary-side coils (Ls) which are individually connected to the respective corresponding drive circuits (2); a plurality of transformer driving units (5) each including a driving switching element (M) that controls supply of electric power to a primary-side coil (Lp); and a power supply control device (6) that provides transformer drive signals (MG) for driving the transformer driving units (5). The power supply control device (6) drives the transformer driving units (5) by transformer drive signals (MG) having different phases.