The present invention discloses a method of loading a control program for a numerical control apparatus, wherein the control program is composed of a plurality of load modules. Each module contains a judgment codes, such as a version number, at the head portion thereof, and is stored in a read/write operation enabling memory, so that each of the judgment codes can be compared with a corresponding judgment code received from an external apparatus by a judgment code comparing means. When the comparison detects different judgment codes, transmission of the new load module corresponding to the discorded judgment codes requested by a modified load module requesting means. Only the substantive portion of the load modules corresponding to the discorded judgment codes received through the comparing means and requesting means need be loaded onto the memory by way of a load means.