A direct AC power converter comprising: a DC link having a first power supply line and a second power supply line, an electric potential lower than an electric potential of said first power supply line being applied to said second power supply line; a first rectifying circuit (5,51) having a plurality of input terminals that are configured to input an AC voltage (Vin) and a pair of output terminals (51c, 51d), each of which is connected to said DC link that are configured to output a rectified voltage (Vrec) of said AC voltage; an inverter configured to convert a voltage applied to said DC link into another AC voltage; and a boost chopper having a capacitor at an output stage; a switch configured to switch discharge and non-discharge from said capacitor to said DC link, wherein a zero-voltage duty (dz) is defined as a time ratio corresponding to a period during which said inverter is configured to adapt a zero-voltage vector regardless of the magnitude of the voltage to be output, a discharge duty (dc) is defined as a time ratio of a conductivity of said switch configured to apply a voltage (Vc) between both ends of said capacitor to said DC link, and a rectifying duty (dr) is defined as a time ratio of conductivity of said rectifying circuit and configured to take a value obtained by subtracting a sum of said discharge duty (dc) and said zero voltage duty (dz) from a value of 1, characterized in that said boost chopper is configured to perform charging into said capacitor at least at a first period being part of a period during which the discharge duty (dc) is larger than 0 when said voltage (Vc) between both ends of said capacitor is larger than said rectified voltage. a DC link having a first power supply line and a second power supply line, an electric potential lower than an electric potential of said first power supply line being applied to said second power supply line; a first rectifying circuit (5,51) having a plurality of input terminals that are configured to input an AC voltage (Vin) and a pair of output terminals (51c, 51d), each of which is connected to said DC link that are configured to output a rectified voltage (Vrec) of said AC voltage; an inverter configured to convert a voltage applied to said DC link into another AC voltage; and a boost chopper having a capacitor at an output stage; a switch configured to switch discharge and non-discharge from said capacitor to said DC link, wherein a zero-voltage duty (dz) is defined as a time ratio corresponding to a period during which said inverter is configured to adapt a zero-voltage vector regardless of the magnitude of the voltage to be output, a discharge duty (dc) is defined as a time ratio of a conductivity of said switch configured to apply a voltage (Vc) between both ends of said capacitor to said DC link, and a rectifying duty (dr) is defined as a time ratio of conductivity of said rectifying circuit and configured to take a value obtained by subtracting a sum of said discharge duty (dc) and said zero voltage duty (dz) from a value of 1, characterized in that said boost chopper is configured to perform charging into said capacitor at least at a first period being part of a period during which the discharge duty (dc) is larger than 0 when said voltage (Vc) between both ends of said capacitor is larger than said rectified voltage.