To provide a preprocessing means for fractional distance with which a simple connection at continuous tangential points between moving command blocks is facilitated and mechanical working is performed at high speed with high accuracy.

A speed control section is provided before and after a pure constant speed section inside a constant speed section, and the processing of fractional distance is performed while using a machining fraction processing means for constituting the final one sampling section in the pure constant speed section by decelerating target speed until the section length of the pure constant speed section becomes the integer multiple of the product of target speed and sampling cycle or a distribution adding fraction processing means for distributing the fractional distance to the constant speed section again by accelerating the target speed while excluding the final one sampling section corresponding to the fractional distance from the pure constant speed section.