PURPOSE: To improve accuracy for copy machining by obtaining the predetermined amount in proportion to the change of a speed instruction value, and providing a shift control means for moving only a model using the obtained value as a position instruction value.

CONSTITUTION: A sub-table 38 for placing only a model 33 is provided on the main table of a copying machine tool, and shifted in the same direction as the shift of a main table with a shift control means by an amount in proportion to the change of a speed instruction value, for example, the delayed amount of a servo system. As a result, a tracer head 31 moves always ahead of a cutter 34, and when an axis speed drops due to the collision of the tracer head 31 with a corner part, the sub-table 38 returns by an amount corresponding to the aforesaid seed drop. The aforesaid return amount corresponds to the bite amount of the tracer head 31 in the axial direction concerned. The shift amount of the cutter 34, therefore, is reduced by the aforesaid bite amount, compared with the tracer head 31, thereby enabling the prevention of the bite of the cutter 34.