PURPOSE: To stabilize the standard of a blade displacement detector and to prevent trouble such that the position in the blade thickness direction of the displacement detector fluctuates at the time of usual cutting by attaching the blade displacement detector to the fixing part of an inner peripheral blade type cutter on the side of the tension head of a blade.

CONSTITUTION: In a plane cutting inner peripheral blade cutting composite processing machine, a blade 25 is rotated at a high speed and, in such a state that the end surface of an ingot W is moved downward from the edge part 25a of the blade 25 by the quantity corresponding to the thickness of a wafer, the ingot W is moved from the almost central position of the blade 25 to the right to cut a wafer to recover the same in a recovery part 40. The non-contact type displacement detector 10 of a displacement detection device 50 is attached to the inner cover 36 of this processing machine through an attaching block 37. At the time of the initial cutting of the ingot, a detector holder is rotated by about 90° up to a position where the distance between the displacement detector 10 and the blade 25 becomes larger than the thickness of the initially cut piece of the ingot.