PURPOSE: To make a work processing correct by providing a grinding device which grinds a cutting tool to work the body to be cut on a work table, and enabling the polishing of the tool without removing the cutting tool from a rotating shaft.

CONSTITUTION: A work W is fixed to a table 2 inside an area S, a cutting tool 9 is rotated via a spindle head 6. And the work W is processed with a column 3 being moved in the fore and aft and horizontal directions, also with the head 6 being moved vertically. In the case of the sharpness of the cutting edge of the cutting tool 9 being reduced, the cutting tool 9 is moved into an area K, after stopping the rotation of the spindle head 6, the cutting edge is fixed and also the grinding wheel 15 of a grinding device 13 located on the same table 2 is rotated, and the cutting edge of a work tool 9 is polished. Therefore the polishing can be executed without removing the work tool 9 from the spindle head 6, and in the case of processing the work W continuously after polishing, it can be worked correctly.