Abstract: A drilling restart control system is for restarting an NC drilling machine for a printed wiring board or the like. A drilling data block provides for a bore diameter, a drilling position, and detection of a complete block. A host computer reads data from a storage medium and the data processing is executed. A series of drilling instructions is stored in a memory with protection against power failure. When a restarting of the drilling operation is indicated, the machining operation is reserved until the data coincides with the contents stored in the memory with protection against power outage.