To form a cylindrical spline formed product with excellent economical efficiency and high workability regardlessly of the material of a stock.

A disklike stock 24 is concentrically interposed between a first die 16 and a second die 18, and they are integrally rotated and also, the outer peripheral surface 88 of a tapered roller 77 having the tapered angle of 60-85° to the surface perpendicular to rotating axis of the second die is pressed to the outer peripheral part of the disk-like stock 24 to form the stock into the tapered shape. Successively, the outer peripheral surface of a straight roller is pressed to the outer peripheral part of the disklike stock 24 formed into the tapered shape together with the first die to form the stock into the cylindrical shape corresponding to the outer peripheral surface of the straight roller. Further, the outer peripheral surface of a spline forming roller 73 provided with a spline forming tooth part corresponding to the spline shape is pressed to the outer peripheral part of the stock 24 formed into the cylindrical shape together with the first die. By this method, the stock is formed into the spline shape corresponding to the spline forming tooth part.