PURPOSE: To realize highly accurate and efficient processing by performing hole processing while supplying a grinding soln. into the central space of a pipe-shaped core grinding wheel under high pressure.

CONSTITUTION: A collet chuch 1 is incorporated in the main shaft of a device to chuck a core grinding wheel 2 and a high pressure grinding soln. is allowed to flow in the chuck 1. An object to be processed is placed on a vacuum chuck table 3 having grinding resistance sensor built therein in order to detect the grinding resistance of the core grinding wheel 2 to be subjected to hole processing. When hole processing is performed, the core grinding wheel 2, the collet chuck 1 and an internal passing soin. are used. By this constitution, highly accurate and efficient processing can be realized and, by performing the detection of load at the same time, synthetic hole processing considering safety is executed. The processing efficiency of 3-min one-hole due to the up-and-down operation of a tool for the keeping accuracy or cooling in conventional ultrasonic processing is enhanced to 20 times. Even in core grinding wheel processing, speed becomes 2-2.5 times and the lift of the core grinding wheel becomes 4.5 times or more.