PURPOSE: To eliminate the need for the correction of the speed of revolution of a motor by changing the reference rotation period of the motor according to a displacement quantity when the displacement quantity due to the loss of a driving system is generated between the rotation period of a rotary shaft for driving a motor corresponding to the rotation period of a motor output shaft and the above-mentioned period.

CONSTITUTION: The reference rotation period of a motor 2 being on object to be stored beforehand and the detected rotation period of the motor 2 to be actually detected are compared, and when a first offset is generated between the reference rotation period and the detected rotation period corresponding to the reference rotation period, the rotation period of the motor 2 is corrected so as to be matched to the reference rotation period. In such a case, when the tape speed is maintained at an object value by a phase servo system 11, the reference rotation period and the detected rotation period are compared, and when a second offset is ganerated between the reference rotation period and the detected rotation period, the reference rotation period is corrected so as to be matched to the detected rotation period. Thus, the second offset can be offset.