To provide a power conversion device which can prevent a load or a power supply from being degraded in their insulation properties by an excessive surge voltage.

In a motor drive system having an LC circuit present between an inverter 2 and a motor 4, a switching element connected to a high potential side terminal of a DC power supply is turned on or off when the output current of the inverter 2 is positive polarity, and a switching element connected to a low potential side terminal of the DC power supply is turned on or off when the output current is negative polarity. Furthermore, a control signal to turn the switching elements on is composed of first, second and third on-signals, so that when the switching elements are switched from an off state to an on-off state, the first on-signal after the off state is output a prescribed pause time later.