In the A.C. electric motor control device of this invention, with the object of improving response to abrupt speed adjustments and load fluctuations, and of improving stability of control under low speed operation, a prescribed current of the inverter circuit is detected and the power factor or power is controlled in accordance with the amount of change in this current.Specifically, a prescribed current of the inverter circuit is detected and the power factor or power is calculated from this detected current value. Using the result of this calculation, together with a command value, control quantities are calculated that determine the output voltage and output frequency of said inverter circuit. Control signals for the switching elements of said inverter circuit are then generated in accordance with these calculated control quantities.