In numerical control processing is executed based on a machining program composed of multiple items of numerical control command data such as numerical command data and G-code data. Each item of the G-code data is expressed in the form of an alphabetic character G, a numerical value folowing G, and a code following the numerical value.
Items of G-code data are inserted in the machining program at suitable locations, subsequently discriminated, and processing specified by the discriminated G-code data executed.
A G-code memory (106) has storage locations each having a plurality of bit locations. Each storage location has an address (00 to 99) corresponding to a different- G-code data numerical value, and each bit position (b, to b 8 ) corresponds to a different G-code data code.