PURPOSE: To shorten time required for alignment by a method wherein the center of a circular substrate is calculated from the distance of an assumed diameter line to rotate the substrate so that a formation angle and position of a notch are calculated from the intersections of an inner peripheral circle at specific positions and the notch.

CONSTITUTION: The reference center of a mount 5 for holding a circular substrate 6 is moved to reach the coordinate origin of a stage 4 side to be an assumed center wherein a plurality of assumed diameter lines passing through the assumed center are specified to detect an edge of the substrate 6 by a reflection sensor 9. Thus the distances of a plurality of the assumed diameter lines are measured to calculated the center of the substrate 6 based on the assumed diameter lines except the shortest assumed diameter line. Then the substrate 6 is transferred from the mount 5 onto pincettes 8 and after the center of the substrate 1 is aligned with the center of the mount 5, the substrate 1 is correctly adjusted to the center position transferred on the mount 5. Then the intersections of an inner peripheral face at specific positions in the substrate 6 and a notch for alignment are detected by a sensor 9 to calculate formation angle of the notch from the intersections to detect the position of the notch.