To provide a wheel bearing device with enhanced fatigue strength and durability by removing a decarburized layer formed between a gear part and a spline part, formed by heat treatment of an inner wheel, and to provide a method for manufacturing the same.

In a wheel bearing device of a third-generation structure, a gear part 8 is integrally formed on an end part outer circumference on the inner side of an inner wheel 5, and a serration 20 to be engaged with a serration 7 of a hub wheel 4 is integrally formed on an end part inner circumference, respectively. The inner wheel 5 is integrally and plastically coupled by a caulking part 21 formed by plastically deforming an end part of a small diameter stepped part 4c radially outward, while a small end face 5d of the inner wheel 5 is butted to a shoulder part 4b of the hub wheel 4. The gear part 8 and the serration 20 of the inner wheel 5 are subjected to surface modification by shot peening, and a lubrication film made of solid lubricant is formed on the gear part 8.