PURPOSE: To provide a flexible tube which is arranged at the exhaust system of an automobile and constituted to have a spring constant and a generating stress both adequate to a flexible tube for an automobile, and prevent the occurrence of a crack.
CONSTITUTION: A bellows part 23 on which crest parts 25 and root parts 27 are alternately formed is formed at the outer periphery of a tube 21 made of a metal and an arcuate part 29 is formed at the top part of the crest part 25 and the bottom of the bottom part 27. Thus, the crest heights of a fourth crest M4 from the end part of the bellows part 23 and following crests are made equal to each other and the crest heights of the third, second, and first crest M3, M2, and M1 are gradually decreased toward an end part. The curvature of radius of an arcuate part 29 formed at the rise part 31 of the first crest M1 is set to a value two or more times as large as the curvatures of radius of the arcuate parts 29 formed at the tops of the fourth crest M4 and following crests.