To provide an alignment device movable from a rest position to a measuring position, providing high static and dynamic strength, having a high performance for preventing deterioration in function failure and accuracy, and aligning a preliminary cut workpiece on a gear finish processing device using a noncontact type measuring probe.

A measuring probe returnable from a measuring position to a rest position protected against contamination is arranged in a holder 5 movably in a radial direction or an axial direction relative to the workpiece, and can turn from a stopper to a stopper using a drive mechanism 11 with hydraulic pressure, air pressure, or an electric motor between the measuring position and the rest position in a face including a workpiece shaft as an element of a parallelogram joint member group A. Accordingly, at the time of moving from a lower terminal position 15 to an upper terminal position 12, an action of a measuring probe 1 relative to an outer periphery of the workpiece can be perfectly prevented.