A power conversion device comprising: - a plurality of upper and lower arms composed of switching elements (Sa, Sb, Sc, Sd) - a reactor comprising: - a magnetic body having a core shape that includes three legs (2i, 2h, 2j), a gap is provided to a center leg thereof; - a DC winding wound around the center leg; - a plurality of coupled windings (2a, 2b) wherein a first winding of the plurality of coupled windings (2a, 2b) is wound around one side leg of the two side legs (2i, 2j), and wherein a second winding of the plurality of coupled windings (2a, 2b) is wound around another one side leg of the two side legs (2i, 2j), and wherein the two side legs (2i, 2j) are located on both sides of the center leg, wherein one end of the DC winding is connected to a voltage source, one end of each of the plurality of coupled windings (2a, 2b) is connected to another end (C, D) of the DC winding, another end of each of the plurality of coupled windings (2a, 2b) is connected to each intermediate connection point between the plurality of upper and lower arms, and wherein DC magnetic fluxes generated by currents of the plurality of coupled windings (2a, 2b) flowing through the DC winding merge with each other in the same direction; wherein AC magnetic fluxes generated by currents of the plurality of coupled windings (2a, 2b) flowing through the DC winding are cancelled out by each other, and - a control device for controlling the switching elements (Sa, Sb, Sc, Sd), wherein the voltage source is composed of an AC voltage source, and a bridge diode connected in parallel to the AC voltage source, a positive electrode of the bridge diode is connected to the one end of DC winding, a negative electrode of the bridge diode is connected to a load, and characterised in that the control device is configured to, for in-phase driving, control the switching elements such that when a power transmission direction is a direction from the bridge diode to the load, the switching elements (Sb, Sd) of the lower arms are subjected to in-phase driving, and when a power transmission direction is a direction from the load to the bridge diode, the switching elements (Sa, Sc) of the upper arms are subjected to in-phase driving. - a plurality of upper and lower arms composed of switching elements (Sa, Sb, Sc, Sd) - a reactor comprising: - a magnetic body having a core shape that includes three legs (2i, 2h, 2j), a gap is provided to a center leg thereof; - a DC winding wound around the center leg; - a plurality of coupled windings (2a, 2b) wherein a first winding of the plurality of coupled windings (2a, 2b) is wound around one side leg of the two side legs (2i, 2j), and wherein a second winding of the plurality of coupled windings (2a, 2b) is wound around another one side leg of the two side legs (2i, 2j), and wherein the two side legs (2i, 2j) are located on both sides of the center leg, - a magnetic body having a core shape that includes three legs (2i, 2h, 2j), a gap is provided to a center leg thereof; - a DC winding wound around the center leg; - a plurality of coupled windings (2a, 2b) wherein a first winding of the plurality of coupled windings (2a, 2b) is wound around one side leg of the two side legs (2i, 2j), and wherein a second winding of the plurality of coupled windings (2a, 2b) is wound around another one side leg of the two side legs (2i, 2j), and wherein the two side legs (2i, 2j) are located on both sides of the center leg, wherein one end of the DC winding is connected to a voltage source, one end of each of the plurality of coupled windings (2a, 2b) is connected to another end (C, D) of the DC winding, another end of each of the plurality of coupled windings (2a, 2b) is connected to each intermediate connection point between the plurality of upper and lower arms, and wherein DC magnetic fluxes generated by currents of the plurality of coupled windings (2a, 2b) flowing through the DC winding merge with each other in the same direction; wherein AC magnetic fluxes generated by currents of the plurality of coupled windings (2a, 2b) flowing through the DC winding are cancelled out by each other, and - a control device for controlling the switching elements (Sa, Sb, Sc, Sd), - a control device for controlling the switching elements (Sa, Sb, Sc, Sd), wherein the voltage source is composed of an AC voltage source, and a bridge diode connected in parallel to the AC voltage source, a positive electrode of the bridge diode is connected to the one end of DC winding, a negative electrode of the bridge diode is connected to a load, and characterised in that the control device is configured to, for in-phase driving, control the switching elements such that when a power transmission direction is a direction from the bridge diode to the load, the switching elements (Sb, Sd) of the lower arms are subjected to in-phase driving, and when a power transmission direction is a direction from the load to the bridge diode, the switching elements (Sa, Sc) of the upper arms are subjected to in-phase driving.