Learning control is performed when carrying out processing by repeating instructions in a pattern cycle. Time/position converting means determines a positional deviation for a prescribed position with respect to a reference position, from the positional deviation determined by sampling, and the reference position output in synchronization with the drive of the servo motor. Corresponding correction data stored in the memory means is added to the positional deviation, and then the result is subjected to filtering processing to update the correction data corresponding to the position. Position/time converting means then determines correction data for the current sampling time, on the basis of the correction data corresponding to the position as stored in the memory means, and the detected reference position. This correction data is processed to compensate for dynamic properties, thereby deriving a correctional quantity, which is added to the positional deviation.