An optimum cutting feed rate of a machine tool is calculated at the outset and a tool path as well as the optimum cutting feed rate calculated is directly output to a driving unit of the machine tool. A relative movement between the work and a tool is made to occur along the tool path at the optimum cutting feed rate for each part of the tool path. To this end, a control system includes a CL data generating unit 32, a CL data memory 33, a driving capability data memory 34, a cutting feed rate data generation unit 35, a cutting feed rate data memory 36, and a controller 42.