An electric power conversion system, comprising: a DC power supply ; a plurality of main circuit switching devices bridge-connected to convert DC of the DC power supply to AC, each respectively having a freewheeling diode connected in reverse parallel thereto; and reverse voltage application circuits (7; 7A to 7E) each respectively for applying a reverse voltage smaller than a voltage of the DC power supply to corresponding freewheeling diode , upon a cutoff of back-flow current of the corresponding freewheeling diode , characterized in that each of the reverse voltage application circuits (7; 7A to 7E) comprises a series connection of: a reverse voltage application switching device having a lower withstand voltage than corresponding main circuit switching device and adapted to turn on upon a reverse recovery of corresponding freewheeling diode , the reverse voltage application switching device being a device having holes as a majority carrier; an auxiliary diode (12; 12A) having a shorter reverse recovery time than the corresponding freewheeling diode ; and a low-voltage DC power supply having a lower voltage than the DC power supply , the corresponding main circuit switching device and the reverse voltage application switching device each driven by an output of the low-voltage DC power supply . a DC power supply ; a plurality of main circuit switching devices bridge-connected to convert DC of the DC power supply to AC, each respectively having a freewheeling diode connected in reverse parallel thereto; and reverse voltage application circuits (7; 7A to 7E) each respectively for applying a reverse voltage smaller than a voltage of the DC power supply to corresponding freewheeling diode , upon a cutoff of back-flow current of the corresponding freewheeling diode , characterized in that each of the reverse voltage application circuits (7; 7A to 7E) comprises a series connection of: a reverse voltage application switching device having a lower withstand voltage than corresponding main circuit switching device and adapted to turn on upon a reverse recovery of corresponding freewheeling diode , the reverse voltage application switching device being a device having holes as a majority carrier; an auxiliary diode (12; 12A) having a shorter reverse recovery time than the corresponding freewheeling diode ; and a low-voltage DC power supply having a lower voltage than the DC power supply , the corresponding main circuit switching device and the reverse voltage application switching device each driven by an output of the low-voltage DC power supply . a reverse voltage application switching device having a lower withstand voltage than corresponding main circuit switching device and adapted to turn on upon a reverse recovery of corresponding freewheeling diode , the reverse voltage application switching device being a device having holes as a majority carrier; an auxiliary diode (12; 12A) having a shorter reverse recovery time than the corresponding freewheeling diode ; and a low-voltage DC power supply having a lower voltage than the DC power supply , the corresponding main circuit switching device and the reverse voltage application switching device each driven by an output of the low-voltage DC power supply . <EOS>