A boot for constant-velocity universal joint is retained to a shaft, which has a general surface, a tapered surface, or a vertical surface instead of the tapered surface, and a major-diameter surface that are disposed one after another in this order and coaxially. The boot includes a minor-diameter cylindrical portion (1), a major-diameter cylindrical portion (2), a tapered wall portion (4), or a vertical wall portion instead of the tapered wall portion, and a bellows (3). The minor-diameter cylindrical portion is retained to the major-diameter surface of the shaft. The major-diameter cylindrical portion is disposed separately away from the minor-diameter cylindrical portion and coaxially therewith. The tapered wall portion is in contact with the tapered surface of the shaft. The vertical wall portion is in contact with the vertical surface of the shaft. The bellows (3) connects the tapered wall portion (4) or the vertical wall portion with the major-diameter cylindrical portion (2) integrally.