To provide a method and device for polishing plate glasses capable of efficiently providing approximately uniform and flat polishing surface by applying an Oscar polishing machine irrespective of the amount of polishing.

A polishing device for plate glass is provided with a lower surface plate 1 which is rotated with its upper surface as a polishing surface 1a, an upper surface plate 2 which is arranged opposedly over the lower surface plate 1 and holds a plate glass material 4, and a rotating arm 3 which supports the upper surface plate 2 rotatably through a supporting shaft 5 at its top end and grinds one surface of the plate glass material 4 by reciprocatedly rotating the upper surface plate 2 within the area around one side of the lower surface plate 1 except for its rotating center part with the position eccentric to one side relative to the rotating center O1 of the lower surface plate 1 taken as a center O2. Also it polishes the plate glass material 4 efficiently within the area on the lower surface plate 1 where peripheral speed is high and less in peripheral speed difference.