To provide a technology for working a curved surface symmetric with respect to a rotation axis capable of working a highly precise axisymmetric aspheric shape without non-axisymmetric errors in a short period of time.

A processing machine 10 is mounted on a Z-axis table 11 for holding an object 50 to be worked on a rotating C-axis 12 and works on the axisymmetric aspheric shape by a machining tool 13 supported on a W-axis 14 mounted on an X-axis table 15. The axisymmetric aspheric shape after the working is measured by an incorporated measuring instrument 20 mounted on the X-axis table 15 to obtain a function f (x, θ) giving a distribution of an error dz from an ideal shape in the Z-axis direction. A working program generated by z=g(x)-f(x, θ) by means of g (x) which defines an original axisymmetric aspheric shape is used for corrective working.