There are provided a curved-surface state evaluating unit for forming evaluation data by arranging, virtually, a tool on a given scheduled path locus not interfering with a processed surface of a processing object and by setting tool path sample points to evaluate a state of the processed surface, a tool position data forming unit having a command speed deciding portion for deciding a command speed, at which the tool is moved, based on evaluation data of the tool path sample points, and a tool position deciding portion for deciding the tool position based on the command speed and a shape of a worked surface such that the tool does not interfere with the worked surface, wherein operation of the curved-surface state evaluating unit and operation of the tool position data forming unit are executed in real time.