A polishing device includes a wafer chuck mechanism which retains a wafer while its plane to be polished faces upward, a polishing pad component which possesses a polishing plane which polishes the wafer, a polishing head, and a shift mechanism which enables a relative displacement of said polishing pad component in relation to the wafer. A fixation and retention mechanism fixes and retains said polishing pad component to the polishing head in a detachable fashion while its polishing plane faces downward. The displacement distance of the shift mechanism ranges from the polishing position of the wafer to the exchange position of the polishing pad component, so that the polishing pad component is automatically exchanged.