Disclosed is a polishing head for a polishing apparatus for polishing a quadrangular substrate using a polishing pad attached to a polishing table, comprising a head body portion, a plurality of elastic bags disposed in a surface of the head body portion, which is to face the polishing table, and a substrate holding plate for holding the substrate, the substrate holding plate being pressed by the elastic bags in a direction away from the head body portion, the head body portion being provided with channels for bags, which are in communication with the respective elastic bags, the polishing head further including at least two support plates disposed between the elastic bags on one hand and the substrate holding plate on the other, the elastic bags being configured to press the substrate holding plate through the support plates.