A control device, for a power conversion device using a three-phase magnetic coupling reactor, includes: a first outer coil; a second outer coil; an inner coil disposed between the first outer coil and the second outer coil; and a core including a first outer core portion around which the first outer coil is wound, a second outer core portion around which the second outer coil is wound, and an inner core portion around which the inner coil is wound. Directions of magnetic fluxes generated in the first outer coil, the second outer coil, and the inner coil are opposite to each other in any combination. In a three-phase operation, the control device controls a value of the current flowing through the inner coil so as to approach values of the currents flowing through the first outer coil and the second outer coil.