A polishing apparatus includes: a rotatable polishing table for supporting a polishing pad having a polishing surface; a top ring head having a top ring; a top ring head cover surrounding the top ring head; a dresser head having a dresser configured to dress the polishing surface; a dresser head cover surrounding the dresser head; a spray nozzle configured to spray a cleaning liquid onto an upper surface of the top ring and an outer surface of the top ring head cover when the top ring is in the substrate transfer position; and a spray nozzle configured to spray a cleaning liquid onto an outer surface of the dresser head cover when the dresser is in the retreated position.