PURPOSE: To fix the peripheral speed of plural cutting places and to improve the working efficiency by fixing the cutting speed of between a work and drill and controlling a cutting tool rotating servomotor for fixing the cutting speed of between the cutting tool and work by matching to the peripheral speed variation of a main shaft.

CONSTITUTION: When a command is given to an arithmetic circuit 10 so as to execute byte working at peripheral speed V1 on the main shaft side, a main shaft actual number of rotations command signal R1 is output, a main shaft servomotor 13 is rotated and driven, and the signal R1 is input to a differential circuit 21. The speed command S2 of the constant peripheral speed of a cutting tool is input from a tool peripheral speed arithmetic circuit to the differential circuit 21 and a byte servomotor 24 is driven by a differential signal R2. On the other hand a drill is fed in X axial direction at a constant pitch corresponding to the rotation of the servo motor 13. Consequently, either byte, drill becomes to be fed by the command value of a fixed pitch per rotation, plural cutting places can be controlled at constant peripheral speed and so the working efficiency is improved.