A direct power converting apparatus, comprising: a positive-side DC power supply line; a negative-side DC power supply line to which a potential lower than a potential applied to said positive-side DC power supply line is applied; input lines (ACLr, ACLs, ACLt) adapted to connect the power converting apparatus to a multi-phase AC power supply functioning as a power supply; input capacitors (Cr, Cs, Ct) each connected between ones of the plurality of input lines (ACLr, ACLs, ACLt); a current-source power converter arranged to convert a multi-phase AC voltage input from said input lines (ACLr, ACLs, ACLt) into a square-wave-shape DC voltage having two potentials, and arranged to supply said positive-side DC power supply line and said negative-side DC power supply line with said square-wave-shape DC voltage having two potentials; a voltage-source power converter adapted to convert said square-wave-shape DC voltage having two potentials between said positive-side DC power supply line and said negative-side DC power supply line into a square-wave-shape AC voltage for output of said square-wave-shape AC voltage to an inductive multi-phase load; a first capacitance device having one end connected to said positive-side DC power supply line; a second capacitance device connected to another end of said first capacitance device and said negative-side DC power supply line; a first diode device connected between said first capacitance device and said second capacitance device, the anode of the first diode being connected to said first capacitance device and the cathode of the first diode connected to said second capacitance device; a second diode device having an anode connected to a point between said second capacitance device and said first diode device and a cathode connected to said positive-side DC power supply line; and a third diode device having an anode connected to said negative-side DC power supply line and a cathode connected to a point between said first capacitance device and said first diode; a discharge resistor connected between said positive-side DC power supply line and said negative-side DC power supply line; and a switching device connected in series with said discharge resistor between said positive-side DC power supply line and said negative-side DC power supply line, arranged to be brought into conduction when a voltage between both ends of said first capacitance device or said second capacitance device exceeds a first predetermined value (Vref-h), and arranged to be interrupted when the voltage falls below a second predetermined value (Vref-L). a positive-side DC power supply line; a negative-side DC power supply line to which a potential lower than a potential applied to said positive-side DC power supply line is applied; input lines (ACLr, ACLs, ACLt) adapted to connect the power converting apparatus to a multi-phase AC power supply functioning as a power supply; input capacitors (Cr, Cs, Ct) each connected between ones of the plurality of input lines (ACLr, ACLs, ACLt); a current-source power converter arranged to convert a multi-phase AC voltage input from said input lines (ACLr, ACLs, ACLt) into a square-wave-shape DC voltage having two potentials, and arranged to supply said positive-side DC power supply line and said negative-side DC power supply line with said square-wave-shape DC voltage having two potentials; a voltage-source power converter adapted to convert said square-wave-shape DC voltage having two potentials between said positive-side DC power supply line and said negative-side DC power supply line into a square-wave-shape AC voltage for output of said square-wave-shape AC voltage to an inductive multi-phase load; a first capacitance device having one end connected to said positive-side DC power supply line; a second capacitance device connected to another end of said first capacitance device and said negative-side DC power supply line; a first diode device connected between said first capacitance device and said second capacitance device, the anode of the first diode being connected to said first capacitance device and the cathode of the first diode connected to said second capacitance device; a second diode device having an anode connected to a point between said second capacitance device and said first diode device and a cathode connected to said positive-side DC power supply line; and a third diode device having an anode connected to said negative-side DC power supply line and a cathode connected to a point between said first capacitance device and said first diode; a discharge resistor connected between said positive-side DC power supply line and said negative-side DC power supply line; and a switching device connected in series with said discharge resistor between said positive-side DC power supply line and said negative-side DC power supply line, arranged to be brought into conduction when a voltage between both ends of said first capacitance device or said second capacitance device exceeds a first predetermined value (Vref-h), and arranged to be interrupted when the voltage falls below a second predetermined value (Vref-L).