To fix the time until an induction motor's start after switching an operation command from ON to OFF by equipping an inverter device with a command input time detecting means and a passage time judging means, and starting the processing to the inputted command after lapse of a predetermined fixed time.

The command input time detection means 3 provided in the controller 2 of an inverter 1 performs the detection of an operation command signal 25 and the detection of a frequency command signal 26, executing the detection of the time at the point when a command is inputted, as interruptive processing. Next, a lapse time judging means 4 judges whether there is a change in the state of each command, and in case that there is a change in each command, it stores the change start time. Then, it measures the lapse time from the stored time, and judges whether the measured lapse time has come to the predetermined fixed time or not. In case the measured lapse time reaches the set lapse time by this judgment, this starts the start processing to the inputted command.