A power conversion device includes a converter-inverter controller for controlling a converter and an inverter. The power conversion device further includes a DC capacitor connected between the converter and the inverter and a DC capacitor voltage detector for detecting a DC capacitor voltage Efc between the connection ends of the DC capacitor. The converter-inverter controller provides variable control on the DC capacitor voltage Efc to the converter on the basis of the motor frequency of an AC motor, the DC capacitor voltage Efc, and a pulse mode. Within a predetermined range of motor frequencies, the converter-inverter controller fixes the PWM modulation factor of the inverter to a value m0 and provides operation control to the inverter, where the value m0 being to reduce a harmonic of a predetermined order included in the output voltage from the inverter.