Abstract: In a PWM inverter having a two-arm structure of upper and lower arms, the dead time is reduced to a minimum for improving the controlling accuracy and linearity under a very small rate of the inverter power output. Also, in the PWM control on a motor, the controlling stability at a lower speed can be increased. Particularly, an improvement for use in a PWM inverter comprises off-state detecting means, each connected to a power switching element in one of the two upper and lower arms of the PWM inverter for detecting the off-state of the switching element and gate means, each provided for receiving an off-state detection signal fed back from the off-state detecting means of the opposite arm connected to the input of corresponding one of the two switching elements and generating a turn-on signal for the other switching element.