A power conversion system comprising: an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for discharging, being connected in series to the discharge resistor; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a voltage detection circuit unit for a switching element that detects voltage between both terminals of the switching element for discharging; a first discharge control circuit that includes a first microcomputer; and a second discharge control circuit that includes a second microcomputer; wherein said first discharge control circuit outputs a control signal to said second discharge control circuit to control switching of the switching element for discharging based on a voltage value of voltage being detected by the voltage detection circuit unit and an active discharge signal to start discharging output from an upper controller; wherein said second discharge control circuit outputs a conduction command signal to achieve conduction of the switching element for discharging for a predetermined period and an interruption command signal to interrupt the conduction of the switching element for discharging after the conduction for the predetermined period, based on the control signal received from the first discharge control circuit via an insulated transmission element, characterized in that after the first discharge control circuit is determined to be in an abnormal state, the second discharge control circuit receives the detected voltage from the voltage detection circuit unit, the detected voltage from the voltage detection circuit unit for a switching element, and the active discharge signal outputted from the upper controller via the insulated transmission element, and the second discharge control circuit outputs the conduction command signal and the interruption command signal based on the detected voltage from the voltage detection circuit unit, the detected voltage from the voltage detection circuit unit for a switching element, and the active discharge signal, wherein the control signal output by the first discharge control circuit is a control signal that has a rising edge and a falling edge, and the second discharge control circuit outputs the conduction command signal or the interruption command signal corresponding to the rising edge and the falling edge, respectively. an inverter circuit unit that converts a direct current power supplied from a direct current source into an alternating current power, the direct current power being supplied to the inverter circuit through a contactor that conducts and interrupts the direct current; a capacitor that smoothes the direct current power; a discharge circuit unit that is connected to the capacitor in parallel, and that includes a discharge resistor for discharging a charge stored in the capacitor and a switching element for discharging, being connected in series to the discharge resistor; a voltage detection circuit unit that detects voltage between both terminals of the capacitor; a voltage detection circuit unit for a switching element that detects voltage between both terminals of the switching element for discharging; a first discharge control circuit that includes a first microcomputer; and a second discharge control circuit that includes a second microcomputer; wherein said first discharge control circuit outputs a control signal to said second discharge control circuit to control switching of the switching element for discharging based on a voltage value of voltage being detected by the voltage detection circuit unit and an active discharge signal to start discharging output from an upper controller; wherein said second discharge control circuit outputs a conduction command signal to achieve conduction of the switching element for discharging for a predetermined period and an interruption command signal to interrupt the conduction of the switching element for discharging after the conduction for the predetermined period, based on the control signal received from the first discharge control circuit via an insulated transmission element, characterized in that after the first discharge control circuit is determined to be in an abnormal state, the second discharge control circuit receives the detected voltage from the voltage detection circuit unit, the detected voltage from the voltage detection circuit unit for a switching element, and the active discharge signal outputted from the upper controller via the insulated transmission element, and the second discharge control circuit outputs the conduction command signal and the interruption command signal based on the detected voltage from the voltage detection circuit unit, the detected voltage from the voltage detection circuit unit for a switching element, and the active discharge signal, wherein the control signal output by the first discharge control circuit is a control signal that has a rising edge and a falling edge, and the second discharge control circuit outputs the conduction command signal or the interruption command signal corresponding to the rising edge and the falling edge, respectively.