Numerical control device

A numeral control device that controls a tool driving unit configured to process a workpiece into an arbitrary finishing shape by performing a plurality of processing operations each of which makes a tool cut into the workpiece and feed the tool, so that the tool moves along a processing locus to perform the processing operations, the numeral control device comprising:

• an initial locus deriving unit configured to derive the processing locus based on the arbitrary finishing shape;
• a processed range acquiring unit configured to acquire a processed range in which the tool has performed the processing operation along the derived processing locus;
• a receiving unit configured to receive a processing instruction for a changed finishing shape different from the arbitrary finishing shape;
• and
• a changed locus deriving unit configured to derive a changed processing locus based on a shape of a changed processed part obtained by excluding the processed range from the changed finishing shape when the receiving unit has received the processing instruction for the changed finishing shape at the time of interruption of the processing along the processing locus.