A drive controller comprising: a converter unit and an inverter section configured to convert a direct current supplied from the converter unit into an alternating current to supply the alternating current to a load, said converter unit comprising: a reactor connected to an alternating current power supply; a converter circuit including two rectifying devices (6a, 6b) and two switching devices (7a, 7b) each switching device (7a, 7b) being connected in parallel to one rectifying device (6a, 6b); a drive section (11a, 11b) configured to drive the converter circuit; a smoothing capacitor configured to smooth a current outputted from the converter circuit; and a control section configured to use a carrier wave of a frequency equal to or lower than 10 kHz to control the drive section (11a, 11b), wherein the control section uses both a signal wave of a modulation factor corresponding to a load and the carrier wave to generate a PWM signal, and provides the PWM signal to the drive section (11a, 11b) to perform PWM converter control for suppressing power line harmonics, and the control section does not perform PWM converter control to turn on and off the switching device (7a, 7b) in a low load region in which the load is relatively low, and performs the PWM converter control in a high load region in which the load is relatively high. a converter unit and an inverter section configured to convert a direct current supplied from the converter unit into an alternating current to supply the alternating current to a load, said converter unit comprising: a reactor connected to an alternating current power supply; a converter circuit including two rectifying devices (6a, 6b) and two switching devices (7a, 7b) each switching device (7a, 7b) being connected in parallel to one rectifying device (6a, 6b); a drive section (11a, 11b) configured to drive the converter circuit; a smoothing capacitor configured to smooth a current outputted from the converter circuit; and a control section configured to use a carrier wave of a frequency equal to or lower than 10 kHz to control the drive section (11a, 11b), wherein a reactor connected to an alternating current power supply; a converter circuit including two rectifying devices (6a, 6b) and two switching devices (7a, 7b) each switching device (7a, 7b) being connected in parallel to one rectifying device (6a, 6b); a drive section (11a, 11b) configured to drive the converter circuit; a smoothing capacitor configured to smooth a current outputted from the converter circuit; and a control section configured to use a carrier wave of a frequency equal to or lower than 10 kHz to control the drive section (11a, 11b), wherein the control section uses both a signal wave of a modulation factor corresponding to a load and the carrier wave to generate a PWM signal, and provides the PWM signal to the drive section (11a, 11b) to perform PWM converter control for suppressing power line harmonics, and the control section does not perform PWM converter control to turn on and off the switching device (7a, 7b) in a low load region in which the load is relatively low, and performs the PWM converter control in a high load region in which the load is relatively high.