PURPOSE: To enable a twisted work to be worked efficiently with high accuracy maintained regardless of lead pitch by holding the work with holding members on both sides of a spindle head and a tail stock so as to be rotated, and controlling a tool in three axes, that is, X, Y and Z axial directions.

CONSTITUTION: One end of a twisted work W is engaged with the engaging pin 11 of a tool 12 so as to be held by the center 6 at the tip end of a spindle head 4, the other end thereof is shifted to the Z axial direction with a cylinder 18 driven so as to be held by the center 19 at the side of a tail stock 14, and the center W1 of the work W shall be offset by the amount of eccentricity 'e' from the rotational center NS of the spindle head. In the second place, the work W is synchronously rotated by a motor 5 via the spindle head 4, a tool T is controlled by motors 33 and 34 in the X and Y axial directions so as to be fed by a motor 32 to the Z axial direction at a high speed V, following which it is returned again when it is positioned at a place where the working operation is completed. The spindle head 4 is closely divided depending on accuracy required, the working operation is performed again while the depth of cutting by the tool T is being maintained at its initial condition, whose working operation is processed accompanied with close division effected starting from the initial working position in order, thereby completing the working operation after one revolution is over.