A method of approach in area cutting includes giving in advance an angle .theta. between a workpiece plane (WPL) and a straight line (SL) connecting an approach starting point (P.sub.A) and a cutting starting point (P.sub.i), and a distance dz between the approach starting point (P.sub.A) and the cutting starting point (P.sub.i) in a direction perpendicular to the workpiece plane. Coordinate values of the approach starting point (P.sub.A) are calculated using the angle .theta. and the distance dz in such a manner that a projection (SL') of the straight line (SL) on the workpiece plane (WPL) is brought into orientation with a direction of a normal line at the cutting starting point (P.sub.i) on a curve (OLC) of the external shape. A tool (TL) is positioned at the approach starting point (P.sub.A) in a rapid-traverse mode, and the tool is subsequently moved to the cutting starting point (P.sub.i) in a cutting-feed mode. Thereafter, cutting is started.