this invention pertains to a polishing apparatus for polishing a semiconductor wafer . the apparatus comprises a storage section that is capable of receiving a workpiece to be polished and a polished workpiece . the polishing unit that polishes the workpiece includes a primary polishing table and a secondary polishing table , wherein the polishing surface of the secondary polishing table is constructed to be arranged such that at least a portion of a surface of the workpiece being polished by the polishing surface of the secondary polishing table extends beyond an edge of the polishing surface of the secondary polishing table . also provided is a film thickness measuring device , which measures the thickness of a film formed on a polished workpiece while the polished workpiece is held by a top ring above a pusher .