SHAFT MEMBER FOR WHEEL ROLLING BEARING DEVICE

[Problem] In a shaft member of a wheel rolling bearing device, local concentration of stress (stress concentration) which is generated by a load applied to flange portions that are formed by cold forging is suppressed. [Means for Resolution] A flange portion which is formed by cold forging is configured by an outer flange portion and an inner flange portion. As viewed in the axial section, the inner flange portion is formed to be thicker than the outer flange portion. The shape of a flange surface which is on a side where a bolt seat 27a is disposed includes: a shape of a concave curved portion which is connected to the outer flange portion, as the shape of the flange surface between a basal end portion of the shape of a vertical surface which has a constant length in a radial direction, in the position of a radially basal end portion, and the outer flange portion; and a convex curved portion 21i which is continuously joined to the concave curved portion 21h, in a radially inner side with respect to the concave curved portion 21h, and the radius of curvature R3 of the convex curved portion 21i is smaller than the radius of curvature R2 of the concave curved portion 21h.