PURPOSE: To simplify the operation of correction by turning a logic processing unit to a correction mode by a contact point for the correction when a slider is positioned at the end of a linear encoder and immediately cancelling the correction mode when it is separated from the end.

CONSTITUTION: The contact points 13 and 14 for the correction are arranged so as to turn the respective contact points 13 and 14 for the correction to an active state by the slider 11 when the slider 11 is positioned at one or the other of the end of the travel. Since the contact points for the correction, the contact points 13 and 14 for turning the logic processing unit 2 to a correction state to be more accurate, are not turned to the active state unless the slider 11 is positioned at the end of the travel, as soon as the slider 11 is separated from the end of the travel, the logic processing unit 2 is returned to a motor control mode without turning a specified contact point to the active state. Thus, the need of displaying the correction mode is eliminated and the operation of the correction is simplified.