To completely eliminate a reduction in effect of strength increased by performing the roll working of a fillet part.

In a method for roll-working the fillet part 5 of a shaft, a final cross-sectional shape (c) of the fillet part 5 is taken as a curved shape without a recess, and a cross-sectional shape (a) thereof before roll working is taken as a shape including a deformation margin during the working. After the roll working is applied to the cross-sectional shape (a), an excess part 15 is cut by machining so as to obtain the cross-sectional shape (c). The deformation margin is precedently made in accordance with the optimal cross-sectional shape (c) taken as the curved shape without the recess, and the roll working is applied in order to crush the deformation margin. Consequently, the conventional recess cannot be generated in the cross-sectional shape (c), the effect of the strength increase brought about by the roll working can be maintained, and an appearance is made favorable.