PURPOSE: To make it possible to process a bowl-shaped wafer by a method wherein when a semiconductor material is cut into a thin piece by pushing the material to a rotating blade and displacement of the cutting blade is detected by means of a sensor, the amt. of displacement of the cutting blade on the peripheral edge of the wafer to be cut is operated and an air pad is worked so as to make this displacement zero.

CONSTITUTION: An ingot 18 is moved toward an inner peripheral blade 16 in the direction X to start cutting. As resistance to cutting becomes larger, the blade 14 tends to be warped. When a sensor 32 detects the displacement of the blade 14, the amt. of displacement of the cut peripheral edge of a semiconductor material to be cut is operated from a relation among the cutting position at that time, the position of a sensor, the position of an air pad 30, the amt. of displacement of the blade detected by the sensor 32 and control of warpage is performed by the air pad 30 so as to make this displacement zero. When the ingot 18 is cut while this operation is performed at each position, as the displacement of the cut edge of the inner peripheral blade 16 to the ingot 18 becomes zero, a bowl-shaped wafer can be processed.