The present invention relates to a restart function with numerical program control device. The numerical controller has a program restart function and acquires program restart block data for resuming and ending suspended machining of a workpiece. The numerical controller analyzes a block of a machining program, and upon determining that a moving path of a tool, which is determined by the block, passes a boundary of a predetermined machining area of each controlled axis of a machine tool, the numerical controller acquires the program restart block data of that block and performs partial machining of the workpiece based on the acquired program restart block data.