PURPOSE: To polish a wafer using a grinding device without causing any dimple by placing the wafer, an outer periphery of which has been tapered, on a chuck table, and sucking and holding the same, and further polishing the wafer while applying a blade tip of a grindstone to a tapered portion of the wafer.

CONSTITUTION: A wafer 12 is placed on a chuck table 11 and is sucked and held, and the surface of the wafer is polished with a grinding device 3. More specifically, a rotating grindstone 10 is lowered and applied to the wafer 12 for polishing of the same into a predetermined thickness. Thereupon, tapered portions l2a, 12b are formed in the wafer 12, so that even if a blade tip 10a of the grindstone 10 strongly strikes an outer peripheral edge of the wafer 12, no relatively large polishing dust is produced, and even when the wafer 12 is demounted from the chuck table 11, such polishing dust does not adhere to the upper surface of the wafer, and further even when the next wafer is placed on and fixed to the chuck table 11 and is polished, no dimple phenomenon is produced.