Provided is a polishing apparatus which comprises a polishing mechanism for polishing a wafer taken out from a cassette, an attaching-detaching device for attaching to and detaching the wafer from the polishing mechanism, a device for cleaning the polished wafer, and a transportation device for transporting the wafer between the cassette, polishing mechanism, attaching-detaching device, and cleaning device. These devices are arranged individually in compartments. A working chamber is divided into a plurality of compartments by means of partitioning devices. A device for polishing a workpiece is set in one of the compartments. The apparatus is also provided with communication devices for internally connecting the adjacent compartments which are divided by the partitioning devices. The apparatus may further comprise devices for individually controlling the respective internal pressures of the compartments or a device for generating an air flow in the form of a laminar flow in each of the compartments.