Abstract: A machining feed rate for machining a workpiece portion to be machined by a machining tool based upon a machining program is set by reading a data of the workpiece portion, by sectionalizing the workpiece portion in an area corresponding to a workpiece shape of the workpiece portion, and by determining a shape change point based upon a workpiece shape of the workpiece portion. The machining feed rate is set for each area and for each shape change point with reference to a predetermined parameter corresponding to an attribute of the each sectionalized area and corresponding to an attribute of the each determined shape change point.