A direct power conversion device, comprising: a first power supply line; a second power supply line configured to be applied with a potential lower than that of said first power supply line; a diode rectifier which has an input side connected with a single-phase AC power supply and an output side connected with said first power supply line and said second power supply line, and which is configured to perform a single-phase full-wave rectification; a first capacitor provided between said first power supply line and said second power supply line; a charge/discharge circuit provided between said first power supply line and said second power supply line on a side opposite to said diode rectifier with respect to said first capacitor; and an inverter inputted with a DC voltage (Vdc) as a voltage between said first power supply line and said second power supply line, wherein said charge/discharge circuit has a buffer circuit including a second capacitor provided between said first power supply line and said second power supply line and a first switch (Sc, D42) connected in series to said second capacitor on a side of said first power supply line between said first power supply line and said second power supply line, a booster circuit which is configured to boost a rectified voltage from said diode rectifier to charge said second capacitor, and a current blocking part provided on said first power supply line or said second power supply line between said first capacitor and said second capacitor and is configured to block flowing of a current from said second capacitor to said first capacitor, said current blocking part is a diode, and characterized in that said booster circuit includes a second diode provided with an anode and a cathode connected between said first switch (Sc, D42) and said second capacitor, a reactor connected between said first power supply line and said anode, and a second switch (S1, D41) connected between said second power supply line and said anode, and said diode is provided on said first power supply line between said first switch (Sc, D42) and said reactor of the booster circuit. a first power supply line; a second power supply line configured to be applied with a potential lower than that of said first power supply line; a diode rectifier which has an input side connected with a single-phase AC power supply and an output side connected with said first power supply line and said second power supply line, and which is configured to perform a single-phase full-wave rectification; a first capacitor provided between said first power supply line and said second power supply line; a charge/discharge circuit provided between said first power supply line and said second power supply line on a side opposite to said diode rectifier with respect to said first capacitor; and an inverter inputted with a DC voltage (Vdc) as a voltage between said first power supply line and said second power supply line, wherein said charge/discharge circuit has a buffer circuit including a second capacitor provided between said first power supply line and said second power supply line and a first switch (Sc, D42) connected in series to said second capacitor on a side of said first power supply line between said first power supply line and said second power supply line, a booster circuit which is configured to boost a rectified voltage from said diode rectifier to charge said second capacitor, and a current blocking part provided on said first power supply line or said second power supply line between said first capacitor and said second capacitor and is configured to block flowing of a current from said second capacitor to said first capacitor, said current blocking part is a diode, and characterized in that said booster circuit includes a second diode provided with an anode and a cathode connected between said first switch (Sc, D42) and said second capacitor, a reactor connected between said first power supply line and said anode, and a second switch (S1, D41) connected between said second power supply line and said anode, and said diode is provided on said first power supply line between said first switch (Sc, D42) and said reactor of the booster circuit.