PURPOSE: To make the surface structure and surface characteristic of a workpiece uniform and good quality by mounting light protective rings with rigidity on the inner and outer circumferential edges of a ring-state polishing sheet with flexibility so as to extend it.

CONSTITUTION: On at least one face of a ring-state polishing sheet 2 with flexibility, abrasive grains are uniformly diffused and fixed. And on the inner and outer circumferential edges of this polishing sheet 2, light protective rings 3 and 4 having rigidity for extending it are mounted from both sides. When this flexible polishing disk 1 is mounted on a polishing device and rotated, it is not deformed because of rigidity of the protective rings 3 and 4 provided for it, and polishing dispersion is prevented. Also, tension of the polishing sheet 2 is maintained uniform without chronological change because of rigidity of the protective rings 3 and 4, and polishing accuracy is improved.