To solve the problem that since a conventional PWM controller for outputting an arbitrary voltage samples and holds a voltage command at each carrier period, a mistake of a voltage output is large, and if a voltage command frequency is near a carrier frequency, the mistake of the voltage output is particularly large.

A voltage command controller 11 outputs twice a voltage command signal 9 during one period of the carrier signal 6, and the signal 9 is held between a lowest point of the signal 6 to a highest point and the highest point to the lowest point. A PWM control unit 5 inputs the signal 6 and the signal 9 held for a half period, compares in amplitude both the inputs, and outputs a PWM signal 10. A drive control unit 23 inputs the signal 10 and operates to turn on, off an inverter 21.