This invention is to provide a processing system suitable for manufacturing an SOI substrate. A processing system includes a scalar robot for conveying a bonded substrate stack held by a robot hand, and a centering apparatus, separating apparatus, inverting apparatus, and cleaning/drying apparatus disposed at substantially equidistant positions from a driving shaft of the scalar robot. When the robot hand is pivoted about the driving shaft in the horizontal plane and moved close to or away from the driving shaft, a bonded substrate stack or separated substrate is conveyed among the processing apparatuses.