Periodic disturbance occurs in current etc. due to offset error and gain error of a current sensor used in a control device. A voltage command value is generated from a current command value and a current detection value by the current sensor in a current control section. The generated voltage command value is inputted to a plant model section, and a virtual current value is calculated. The virtual current value is inputted to a periodic disturbance observer via a coordinate transform section, and a compensation value is calculated. The compensation value is superimposed on the current detection value via a coordinate inverse-transform section, and the current detection value of the current sensor is corrected.
