To provide a groove processing device for automatically carrying out the groove processing of a taper column material.

The position of a cutter T is restrained by a copy roller R, which is abutted to a peripheral face of a work W and rolls. When the groove processing is carried out with this cutter T, a setting control means C is provided to adjust the position of the copy roller R against the cutter T, so as to control the above-mentioned setting position in correspondent to the slope level of the peripheral face of the work W.