PURPOSE: To work an outer periphery having composite elliptic and tapered surface without exchanging cams by rotating a cutter and a work synchronously and moving them in the axial direction of the work and the direction perpendicular thereto by a master cam moved axially by numerical control and the numerical control.

CONSTITUTION: A tool rest 6 is pivotably connected to a pivot 5 orthogonal to a plane including both axes of a spindle 1 of a feed table 4 and rotary shaft 2 rotated in synchronization with said spindle. Also, a master cam 11 is inserted on an arbor 2a to be rigid rotationally and moved axially by numerical control so that a cutter 7 is moved in the direction perpendicular to the axes in proportion to the movement of a stylus 9 contacting said cam. On the other hand, the table 4 can be movably subjected to numerical control by a motor 41 in the direction perpendicular to the axis and by a motor 42 axially. Thus, an ellipse can be worked by moving axially the cam 11 such that the elliptic portion corresponding to the eccentricity varied axially of a piston 14 contacts the stylus 9, and at the same time a tapered portion can be worked by moving a table 14 in the direction perpendicular to the axis.