A flexible tube includes a bellows tube, an interlock tube placed inside the bellows tube, and upstream-side and downstream-side joint pipes coupled to opposite ends of the bellows tube. Diameters of fixing end portions located at opposite ends of the interlock tube are made larger than a diameter at a middle portion of the interlock tube, extension portions of the upstream-side and downstream-side joint pipes are fitted and fixed to inner peripheral surfaces of the fixing end portions of the interlock tube, and a depth of each of valley portions of a bellows portion of the bellows tube located over the fixing end portions is smaller than a depth of other valley portions of the bellows portion. Accordingly, it is possible to achieve the downsizing of the flexible tube that is connected to an exhaust system being continuous with an engine to dampen vibrations in the axial direction of the exhaust system.