Patent ID: 7056219

Claim:
A constant velocity joint boot comprising: a larger cylindrical portion; a smaller cylindrical portion held by a shaft coaxially with the larger cylindrical portion and being smaller in diameter than the larger cylindrical portion, and a conical bellows portion for connecting the smaller cylindrical portion and the larger cylindrical portion integrally with respect to each other; wherein the larger cylindrical portion includes: an inner peripheral surface for being fitted to a mating member having a noncircular cross-section, provided with a thick-walled portion and a thin-walled portion continuing in a circumferential direction of the larger cylindrical portion, and an outer peripheral surface having a circular cross-section, provided with a fastening face to which a ring-shaped fastening member is fastened, wherein the fastening face is located at the bottom of a shallow groove, a ring groove coming full circle around the outer peripheral surface and opening at the fastening face, wherein the ring groove is formed beneath the fastening member, and at least one endless lip member coming full circle around the inner peripheral surface for being press contact with the mating member, and the ring groove is formed at a position shifted from a position opposing a backside of the lip member.