PURPOSE: To obtain a small-warped wafer by detecting severing resistances through which single crystal ingot is influenced, and lowering the severing speed when it exceeds a predetermined value, at the same time, controlling a slicer with an inner peripheral blade for increasing rotating speed thereof.

CONSTITUTION: A main shaft motor 4 is rotated for rotation-driving a slicer 1 with an inner peripheral blade and, by means of an ingot dividing unit 8, a single crystal ingot 6 is shifted in the C direction at only predetermined quantity. Next. by driving a cut-in forwarding unit 5, it is shifted in the B direction and severed in the axially intersectional direction by the blade tip 2a of a rotating blades 2. At this time, the severing resistances by which the single crystal ingot 6 may be influenced is detected by a voltage type cutting dynamometer 10, or the deviation of the blade 2 is detected by a deviation measuring displacement gauge 11 and, by inputting them into a controller 9 and then feeding back the servering resistances to the cut-in speed and the speed of the slicer 1 with inner peripheral blade 1, the severing resistances are restrained at a constant value or below, thus obtaining a small-warped semiconductor wafer W by restraining the blade 2 into small deviation.