An electric power conversion device of an embodiment includes the electric power conversion device expressed as an equivalent circuit including, a power supply, a first parasitic inductance, a first diode; a second parasitic inductance connected to the first diode in series, a second diode connected to the first diode in parallel, a third parasitic inductance connected to the second diode in series, a switching element, a gate circuit, and a load. The equivalent circuit includes a first circuit loop and a second circuit loop. The first circuit loop includes the power supply, the first parasitic inductance, the first diode, the second parasitic inductance, the switching element, and the gate circuit. The second circuit loop includes the power supply, the first parasitic inductance, the second diode, the third parasitic inductance, the switching element, and the gate circuit.