A power conversion device (101,201,501,512,513,522) which includes a plurality of semiconductor switch elements (SW,SWu,SWv,SWw,SWx,SWy,SWz) and is configured to drive, by controlling turning on or off the semiconductor switch elements, a three-phase motor, the three-phase motor being configured to be connected to the power conversion device by three-phase cables, the power conversion device comprising: a first, forward converter circuit which is configured to convert alternating current power from a power source into direct current power; a second, reverse converter circuit comprising three output terminals and three half-bridge circuits to control current to be supplied to the three-phase motor; wherein each of the half-bridge circuits is associated with one of the output terminals and comprises an upper arm and a lower arm, each of the arms comprising one of the plurality of semiconductor switch elements, and each of the output terminals is to be connected to one of the three-phase cables, a plurality of driver circuits (SD,SDu,SDv,SDw,SDx,SDy,SDz) configured to drive the plurality of semiconductor switch elements of the half-bridge circuits; a control circuit (105,205) configured to control the driver circuit, wherein a direct current voltage is derived from the direct current power; a current measurement unit configured to measure output current values of a plurality of output terminals of the three output terminals of the second converter circuit; and an information output unit configured to notify an inner situation of the device to an outside, wherein, when a short circuit occurred in the cable or the motor is inspected, the control circuit is configured to turn on the semiconductor switch elements, one of which is on an upper arm and the other one of which is on a lower arm of a different half-bridge circuit than the upper arm to generate a current for short circuit investigation in the cable, and is configured to calculate a round-trip inductance value of the cable on the basis of a time during which both the switch elements are turned on and a current measurement value of the current measurement unit, and is configured to determine the short circuit location from the round-trip inductance value, and wherein the information output unit is configured to notify a determination result of the short circuit location to the outside, characterized in that the control circuit is configured to control the direct current voltage to be supplied to the second converter circuit to reduce the direct current voltage to be supplied to the second converter circuit to a voltage lower than the direct current voltage to be supplied when the motor is driven. a first, forward converter circuit which is configured to convert alternating current power from a power source into direct current power; a second, reverse converter circuit comprising three output terminals and three half-bridge circuits to control current to be supplied to the three-phase motor; wherein each of the half-bridge circuits is associated with one of the output terminals and comprises an upper arm and a lower arm, each of the arms comprising one of the plurality of semiconductor switch elements, and each of the output terminals is to be connected to one of the three-phase cables, a plurality of driver circuits (SD,SDu,SDv,SDw,SDx,SDy,SDz) configured to drive the plurality of semiconductor switch elements of the half-bridge circuits; a control circuit (105,205) configured to control the driver circuit, wherein a direct current voltage is derived from the direct current power; a current measurement unit configured to measure output current values of a plurality of output terminals of the three output terminals of the second converter circuit; and an information output unit configured to notify an inner situation of the device to an outside, wherein, when a short circuit occurred in the cable or the motor is inspected, the control circuit is configured to turn on the semiconductor switch elements, one of which is on an upper arm and the other one of which is on a lower arm of a different half-bridge circuit than the upper arm to generate a current for short circuit investigation in the cable, and is configured to calculate a round-trip inductance value of the cable on the basis of a time during which both the switch elements are turned on and a current measurement value of the current measurement unit, and is configured to determine the short circuit location from the round-trip inductance value, and wherein the information output unit is configured to notify a determination result of the short circuit location to the outside, characterized in that the control circuit is configured to control the direct current voltage to be supplied to the second converter circuit to reduce the direct current voltage to be supplied to the second converter circuit to a voltage lower than the direct current voltage to be supplied when the motor is driven.