To provide groove forming method and device can form grooves having a predetermined shape on the outer peripheral face of a belt sleeve for a short time.

First, a cutter 26 is made to abut on the outer peripheral face of the belt sleeve 1 traveled by rolls 21, 22, to cut and form preparatory grooves 9 extended to the sleeve circumferential direction on the outer peripheral face. Next, a honing stone 28 with projecting parts 28a formed to have shapes corresponding to the preparatory grooves 9 is made to abut on the outer peripheral face of the belt sleeve 1 and the outer peripheral face of the belt sleeve 1 including the inner faces of the preparatory grooves 9 is ground, to form V-grooves 8 from the preparatory grooves 9.