A numerical controller, which can handle information on a use tool, calculates the shape of a workpiece being machined, based on an input machining program, shape information of the use tool, shape information of a unmachined workpiece, and a tool trajectory, and sets, as a movable range of the tool, a range in which the tool never contacts the workpiece being machined, based on the calculated shape of the workpiece being machined, if manual operation is performed during machining.

A numerical controller which performs program restart after machining is stopped in the middle of a machining cycle is provided with a program restart unit. The numerical controller can use the program restart unit to acquire a restart position located in a machining area defined by the machining cycle, create a new machining area by dividing the defined machining area in the restart position, and restart the machining for the new machining area.

A numerical controller, which can handle information on a use tool, calculates the shape of a workpiece being machined, based on an input machining program, shape information of the use tool, shape information of a unmachined workpiece, and a tool trajectory, and sets, as a movable range of the tool, a range in which the tool never contacts the workpiece being machined, based on the calculated shape of the workpiece being machined, if manual operation is performed during machining.

A numerical controller which performs program restart after machining is stopped in the middle of a machining cycle is provided with a program restart unit. The numerical controller can use the program restart unit to acquire a restart position located in a machining area defined by the machining cycle, create a new machining area by dividing the defined machining area in the restart position, and restart the machining for the new machining area.

In restarting automatic operation after a machining program or machining conditions are changed or manual intervention is performed while the automatic operation is suspended, a machining path based on simulated operation is drawn to check the change for correctness. A drawing path of an unmachined part is reconstructed by, for example, recalculating a check drawing path at or behind a program stop position, and the reconstructed drawing path is redrawn.