Method of and apparatus for controlling machine tool for restarting automatic operation

A machine tool controlled to restart automatic operation for machining a workpiece from an interrupted point after the machine tool, which has been automatically operated by NC program commands, is caused to interrupt the automatic operation. The NC program commands are classified into a plurality of main groups with respect to the contents of motions for changing the machine state of the machine tool. When the automatic operation of the machine tool restarts after the automatic operation has been interrupted halfway, an order of execution of the NC program commands is determined such that the main groups are arranged in a prescribed order of execution, for automatically generating a machine state restoration command. The automatic operation of the machine tool can restart from the interrupted point without the need for the operator to manually generate or correct a command for restoring the machine tool to its machine.