The present invention provides an apparatus for polishing wafers, wherein high work efficiency in handling a polishing plate is achieved with high flatness finish of the polished wafers. The apparatus has a polishing plate 1 composed of two plates 2, 3, which are superimposed in tight adhesion with each other. The thickness of the polishing plate 1 is adjusted to such a value that the polished wafers may be finished with high flatness across the polished surface. An upper plate 2 is mounted to a top ring 4 by means of a a plurality of rigid supporting member 7 consisting of a hook-shaped plate holding portion 7a and a top ring fixing portion 7b such that a predetermined clearance is left between the upper surface of the upper plate 2 and a flexible thin plate 5 arranged on the lower portion of the top ring 4. The upper and lower plates 2, 3 are polished to be flat and smooth across one side surface to be superimposed of each thereof and then the upper plate 2 and lower plate 3 are superimposed with each other in tight adhesion by surface tension of a liquid. <IMAGE>