To provide a DC-DC converter that can output a desired voltage and can obtain excellent followability even when an output frequency is increased.

A DC-DC converter 100 comprises single-phase bridge inverters 1 and 2 and a transformer 3 insulating between the single-phase bridge inverters 1 and 2. A control circuit 10 controls switching elements Q11 to Q14 and Q21 to Q24 so that the phase at the center of the period in which a voltage V1 is output to an AC side of the single-phase bridge inverter 1 and the phase at the center of the period in which a voltage V2 is output to an AC side of the single-phase bridge inverter 2 are equal to each other.