To provide an apparatus forming a spiral groove to a round bar with a relatively simple structure.

There is provided a spiral groove forming apparatus forming a spiral groove with a constant curvature on the surface of a columnar body, comprising: a column rotatingly holding means holding the columnar body and rotating the same around a center axis by a driving means; a cutting means holding a cutting blade provided with an edge at an outer circumferential edge and rotating the cutting blade with a track of an edge end passing on a circumference; a cutting blade holding means holding the cutting means with the edge end of the cutting blade reaching a bottom of the groove, a plane including the circumference where the track of the edge end passes being in parallel with the direction of the groove at a contact point of the groove with the edge end; and a parallel movement fixing means fixing the cutting blade holding means movably in parallel with the center axis.