To provide a motion control method of a grinding tool and a data origination method for motion control on a robot to eliminate mechanical impact etc., generated in accordance with a speed change during positional movement of the grinding tool by copying control motion.

A track data 102 for positional movement control and a track data 103 for attitude maintenance control are separately and independently provided, and motion of a grinding tool is controlled by using each of these track data 102, 103 under a motion control method of a robot to carry out positional movement control of the grinding tool by the track data 102 set by copying a shape of a molded surface of a work and attitude maintenance control of a head end part for grinding of the grinding tool.