A method and apparatus for controlling the feed speed of a machine in a numerical control system having a manual pulse generator for generating pulses in response to a manual operation. The numerical control system numerically controls the machine by supplying the machine with the generated pulses as feed pulses in a manual feed mode and with feed pulses corresponding to a commanded feed speed in modes other than the manual feed mode. The commanded feed speed is modified in accordance with an override quantity stored in a register. The method includes selectively designating the modes other than the manual feed mode, changing the override quantity, which is stored in the register, based on the pulses generated by the manual pulse generator and in accordance with the designated mode, and modifying the commanded feed speed in accordance with the override quantity stored in the register.