PURPOSE: To suppress the natural vibration of a machine and to improve work accuracy by converting the time sequential data of a tool feeding axis coordinate to corrected time sequential data reduced the frequency component of a prescribed frequency band containing the natural frequency of the machine.

CONSTITUTION: On a RAM 32, an NC data area 321 for storing NC data, profile data area 322 for storing the profile data of a workpiece, spindle coordinate time sequential data area 323 for storing the time sequential data of a spindle coordinate provided by decomposing the profile data, tool feeding axis coordinate time sequential data area 324 for storing the time sequential data of the tool feeding axis coordinate, digital filter characteristic area 325 for storing the characteristic of a digital filter, and corrected time sequential data area 326 for storing the corrected time sequential data of the tool feeding axis coordinate processed by the digital filter are formed. The characteristic of the digital filter is a function reducing the frequency band gain containing the natural frequency of the machine rather than the other area just for several %.