A boot is made of a resin for covering a ball joint interposed between a
larger diameter mating member and a small diameter mating member,
including a large diameter attachment portion fixed to the large diameter
mating member, a first bellows portion continuous to the large diameter
attachment portion, a second bellows portion which is continuous to the
first bellows portion and in which at least a bottom inner peripheral
diameter thereof is not larger than that of the first bellows portion and
a rigidity in a radial direction thereof is lower than that of the first
bellows portion, a taper bellows portion continuous to the second bellows
portion, and a small diameter attachment portion continuous to the taper
bellows portion and fixed to the small diameter mating member.