The present invention provides a polishing head including: an annular rigid ring; an elastic film bonded to the rigid ring; and an upward and downward movable mid-plate, the mid-plate defining a first sealed space together with the rigid ring and the elastic film; an incompressible fluid enclosed in a sealed space; and a mid-plate positioning device for adjusting vertical position of the mid-plate, to hold a back surface of a workpiece on a lower surface of the elastic film and polish a front surface by bringing the front surface into contact with a polishing pad attached to a turn table, wherein the mid-plate can adjust a shape of the lower surface of the elastic film by adjusting the vertical position of the mid-plate. The polishing head polishes a workpiece without generating surface defects on the workpiece surface and easy detachment of the workpiece from a polishing pad after polishing.