By using a configuration comprising sampling means for sampling block end information about each system program, means for identifying a resumption block and a resumption position of each system based on the block end information of each system at the time of a machining halt, and means for calculating information about a synchronous relation between the systems from the block end information of each system and resuming and starting each system based on this calculated result when machining is resumed from the resumption position, it is constructed so that the synchronous relation between the systems can be restored to resume the machining even in a numerical control apparatus in correspondence with multiple systems.