An angle data discriminating method in a method of creating NC machining data by entering a direction for each block (b.sub.1 -b.sub.5) of a part profile through use of a profile symbol key thereby to specify the part profile, followed by entering a dimension for each block of the part profile and using these entered data to create the NC machining data, the method having a first step of specifying dimensions of straight line elements (L.sub.3, L.sub.4) in predetermined blocks (b.sub.3, b.sub.4) by data including at least angles of intersection between the straight line elements and a base line (Z axis), and a second step of recognizing, by using the angles and the directions of the straight line elements in the blocks, that the straight line element lies on a straight line obtained by rotating the base line about the points of intersection in predetermined directions and through predetermined angles.