A power conversion device which includes a plurality of semiconductor switch elements and drives a three-phase motor connected by three-phase cables by controlling the switch elements on or off, the power conversion device comprising: a converter circuit, which is configured to convert an AC power from a power source into a DC power; an inverter circuit, which is configured by three half bridge circuits to control a current which is supplied to the motor; a plurality of driver circuits, which are configured to drive a plurality of switch elements of the half bridge circuit; a control circuit, which is configured to control the driver circuit; a current measurement unit, which is configured to measure output current values of a plurality of phases of the inverter circuit; and an information output unit, which is configured to notify an outer side of an inner situation of the power conversion device, wherein respective ground loops exist between the power source, each phase of the three-phase motor, and inverter circuit; and wherein, when a ground fault site occurring in the cable or the motor is inspected, and the power conversion device is characterized by: the inverter circuit being configured to simultaneously turn on the plurality of switch elements of any one of upper arms and lower arms of the three half bridge circuits to generate a current to the plurality of connection cables, the current measurement unit being configured to measure output current values of a plurality of phases in a period when the switch elements are simultaneously turned on or immediately after the period, the control circuit being configured to determine a ground fault site on the basis of a current ratio of a maximum value and a minimum value of the output current values of the plurality of phases, such as to determine a location of the ground fault on the cable and/or inside the motor; wherein the maximum current is derived from a current measurement in a ground current loop including the faulty phase, and the minimum value of the output current value is derived from a current measurement in a ground current loop not including the faulty phase, and the information output unit notifies an outer side of a result of the determination. a converter circuit, which is configured to convert an AC power from a power source into a DC power; an inverter circuit, which is configured by three half bridge circuits to control a current which is supplied to the motor; a plurality of driver circuits, which are configured to drive a plurality of switch elements of the half bridge circuit; a control circuit, which is configured to control the driver circuit; a current measurement unit, which is configured to measure output current values of a plurality of phases of the inverter circuit; and an information output unit, which is configured to notify an outer side of an inner situation of the power conversion device, wherein respective ground loops exist between the power source, each phase of the three-phase motor, and inverter circuit; and wherein, when a ground fault site occurring in the cable or the motor is inspected, and the power conversion device is characterized by: the inverter circuit being configured to simultaneously turn on the plurality of switch elements of any one of upper arms and lower arms of the three half bridge circuits to generate a current to the plurality of connection cables, the current measurement unit being configured to measure output current values of a plurality of phases in a period when the switch elements are simultaneously turned on or immediately after the period, the control circuit being configured to determine a ground fault site on the basis of a current ratio of a maximum value and a minimum value of the output current values of the plurality of phases, such as to determine a location of the ground fault on the cable and/or inside the motor; wherein the maximum current is derived from a current measurement in a ground current loop including the faulty phase, and the minimum value of the output current value is derived from a current measurement in a ground current loop not including the faulty phase, and the information output unit notifies an outer side of a result of the determination. the inverter circuit being configured to simultaneously turn on the plurality of switch elements of any one of upper arms and lower arms of the three half bridge circuits to generate a current to the plurality of connection cables, the current measurement unit being configured to measure output current values of a plurality of phases in a period when the switch elements are simultaneously turned on or immediately after the period, the control circuit being configured to determine a ground fault site on the basis of a current ratio of a maximum value and a minimum value of the output current values of the plurality of phases, such as to determine a location of the ground fault on the cable and/or inside the motor; wherein the maximum current is derived from a current measurement in a ground current loop including the faulty phase, and the minimum value of the output current value is derived from a current measurement in a ground current loop not including the faulty phase, and the information output unit notifies an outer side of a result of the determination.