A hub wheel (21) and an outer joint member (3) are coupled to each other through intermediation of a recess-projection fitting structure (M). The recess-projection fitting structure (M) can be separated by being applied with a pulling-out force in an axial direction under a state in which a bolt member (30) is removed, and can be re-formed by re-screwing the bolt member (30) into a bolt hole (5d). The hub wheel (21) comprises a receiving portion (23a) for receiving the bolt member (30). The shaft portion (5) has a small diameter portion (5a) serving as a fit-in portion to be fitted along an inner periphery of the receiving portion (23a) under a state in which the recess-projection fitting structure (M) is formed. The small diameter portion (5a) is used as a part for confirming the accuracy and the state of the recess-projection fitting structure (M).