PURPOSE: To prevent uneven wear of a driving member by constituting a machine tool so as to fix a workpiece mounting base to a shaft on a U-axis, arrange a separate shaft in parallel to this shaft, connect the shafts with a gear type belt and connect the gear belt with a ball screw shaft to be driven by a motor.

CONSTITUTION: A main shaft 4 is rotatably mounted on a plate 1 and a pivot table is fixed to the shaft 4 with a screw. A second shaft 14 is arranged side by side by making the shaft 14 apart from this shaft 4, each of both the shafts 4, 14 is provided with each of gear type plate 10, 13 and both of the shafts 4, 14 are connected by extending a gear belt 12. A linear part of this gear belt 12 is engaged with a screw part 25 of a ball screw shaft 31 extended in parallel. The ball screw shaft 31 is rotated by a servo motor 38, the gear type belt 12 is driven in a prescribed direction according to the rotation amount, and the shafts 4, 14 and further the pivot table are rotated in the prescribed direction.