A boot for constant-velocity universal joint includes a major-diameter fastener, a minor-diameter fastener, and a bellows. The bellows includes a first root, a first crest, a second root, a second crest, a third root, a third crest, a fourth root, a fourth crest, a fifth root and a fifth crest. The first crest, the second crest, the third crest, the fourth crest and the fifth crest have a top, respectively, and the tops of the second crest, third crest and fourth crest are disposed on an outer peripheral side with respect to a line L1, which the tops of the first crest and fifth crest make there between, in a cross section involving the central axis of the bellows.