BEARING DEVICE FOR WHEEL

An object of the present invention is to provide a wheel bearing apparatus which can prevent generation of cracks during the face spline forming process. The present invention provides a wheel bearing apparatus in which a double row rolling bearing and a constant velocity universal joint are detachably united, the double row rolling bearing comprising an outer member formed on its outer circumference with a body mounting flange to be mounted on a body of a vehicle and its inner circumference with double row outer raceway surfaces; an inner member including a hub wheel and at least one inner ring, the hub wheel being integrally formed with a wheel mounting flange on its one end and an axially extending cylindrical portion and the inner ring being press-fitted onto the cylindrical portion of the hub wheel, the inner member being formed with double row inner raceway surfaces to be oppositely arranged to the double row outer raceway surfaces; and double row rolling elements rollably disposed between the double row outer raceway surfaces of the outer member and the double row inner raceway surfaces of the inner member; the inner ring being axially immovably secured by a caulked portion formed by plastically deforming the end of the cylindrical portion radially outward; the constant velocity universal joint having an outer joint member including a cup-shaped mouth portion, a shoulder portion forming a bottom of the mouth portion, and a shaft portion axially extending from the shoulder portion and formed on its inner circumference with female thread all of which are integrally formed; and end faces of the shoulder portion of the outer joint member and the caulked portion being formed with face splines respectively to join the double row rolling bearing and the constant velocity universal joint in a torque transmittable manner characterized in that the face spline of the caulked portion has a portion in which a tooth height of the tooth space of a portion radially outer than the pitch circle diameter is set lower than that of other portions.