Control device of AC motor

A control device of a three-phase AC motor includes: an inverter for driving the motor; a current sensor for sensing a sensor phase current of the motor; and a controller for controlling the motor. The controller includes: a current estimation device for estimating d-axis and q-axis current estimated values based on the sensor phase current and an electric angle of the motor; and a zero-crossing interpolation device for interpolating the d-axis and q-axis current estimated values by fixing the d-axis and q-axis current estimated values when the sensor phase current is in a zero cross range, which includes a zero point, so that the sensor phase current crosses the zero point, and for outputting interpolated d-axis and q-axis current estimated values as fixed d-axis and q-axis values, which are used for a feedback control relating to current flowing through the motor.