A commanded speed is acquired by a command program analysis unit, an override is acquired by an override input unit, and the override before input is changed in steps by a stepwise override change unit to the override that is input, in a predesignated time or by a predesignated change amount, and outputs the override changed as an actual override. The actual override is acquired by a speed operation unit in an interpolation cycle from the stepwise override change unit and the commanded speed is multiplied by the actual override to calculate a feed speed.