workpiece surface 60 fig4 a is a plan view which shows one example of the shape of the workpiece surface after cutting while fig4 b is a cross sectional view cut along the line b b of fig4 a in fig4 a the workpiece surface 60 is shown by an xy plane for example by making the tool 54 relatively move on the xy plane along the machining points p0 as shown by the arrows pa the shape of the workpiece surface of fig4 a is obtained the respective machining points p0 are points which express target positions of the centers 54 b which are reference points of the tool 54 when machining the workpiece i e machining command points for generating a tool path the arrows pa correspond to the tool path the machining program also includes position data of the machining points p0 which are sequenced along the tool path pa and data of the amount of tool rotation the distance u03b4p between the machining points p0 p0 along the arrows pa corresponds to for example the amount of one blade of feed and thus the tool 54 rotates by one blade 39 s worth of angle between the machining points a distance u03b4y between the machining points p0 p0 in the y axial direction corresponds to an amount of pick feed in the present embodiment a single blade ball.