Abstract: An aligner includes a driving pulley connected to a motor, a toothed belt hung with respect to a driven pulley connected to a spindle, and a pulley detection sensor detecting the rotation position of the driven pulley. Each time the driving pulley rotates the driven pulley once, the misalignment in the direction of rotation of the driven pulley is detected and a correction value of the rotational misalignment of the driven pulley is calculated based on the driving and driven pulleys having a known rotation ratio. In a case where the rotation angle information of the driving motor is lost, detection data for calibration is created so that a correction value corresponding to the current phases of the driven pulley and the toothed belt after origin search is searched for.