There is provided an AC motor controller capable of detecting an abnormal state of a motor cable while an AC motor is operating without using a special circuit but using a processor.The AC motor controller includes an AC motor; an inverter for driving the AC motor with a motor current through a motor cable; and a motor current detector for detecting the motor current flowing in the motor cable of the AC motor, in which a processor detects an abnormal state of the motor cable such as an inter-phase short circuit and an open circuit based on the motor current detected by the motor current detector.