A rivet is provided which includes axially opposite end portions at least one
of
which is more likely to be deformed radially outwards than a remaining portion
thereof, and the remaining portion is more resistant to a load applied in an axial
direction of the rivet than the axially opposite end portions. As one example,
the rivet includes a head portion and a cylindrical portion that extends from the
head portion, and a recess is formed in the head portion so as to be open to a
top surface of the head portion.