A numerical control apparatus having both a large capacity non-volatile magnetic bubble memory (1) and a high-speed volatile IC memory (2) for storing machining program data. When power is supplied from a power supply to the numerical control apparatus, machining program data stored in the magnetic bubble memory (1) is transferred to, and stored in, the IC memory (2) through an interface circuit (4) which administers the transfer of data between the memories (1) and (2). A processor (3) accesses the IC memory (2) to execute numerical control processing.