To provide a device and a method for polishing both faces of a workpiece capable of manufacturing such a workpiece that allows a surface and a rear surface to be distinguished easily by easily controlling luster of one polishing face of the workpiece without reducing a polishing rate for the workpiece.

This both face polishing device for a semiconductor wafer has an upper surface plate 3 and a lower surface plate 5 provided with polishing cloths 2, 4, a disc-shaped carrier 6 which is arranged between both surface plates 3 and 5 and in which a storage hole 9 storing the workpiece W whose both faces are polished is provided and a driven gear part 10 is formed in an outer fringe part, and a sun gear 7 and an internal gear 8 meshing with the gear part 10 of the carrier 6 to make the carrier 6 perform planetary movement. Furthermore, it has an abrasive supply device 11 supplying abrasive S from a polishing face Wa on one side of the workpiece W and a polishing inhibitor supply device 12 supplying polishing inhibitor A to a polishing face Wb on the other side.