To provide a tightening tool for holding a fitted member by the diameter expansion part of a cylindrical body and a flange, which does not require a set of nuts in the molding of an elastic cylindrical body and a skill for fastening by a bolt, etc., which can maintain an absorption property of the vibration of a low frequency area following the diameter expansion of the elastic cylindrical body in a favorable state.

A tightening tool 1 is provided with an elastic hollow cylindrical body 2 having a flange 9 on its one end and an insertion body 3 in which the diameter of one part of the cylindrical body is expanded by receiving a force for compressing in the axial direction to a flange side in the other end side of the cylindrical body. A first fitted member 5 is held by the diameter expansion part 15 of the cylindrical body and the flange 9 and the second fitted member 6 is held by a bolt 14 and the flange 9 and both fitted members are connected. The insertion body 3 is inserted in the cylinder part of the cylindrical body 2. The inner diameter of the low end side of the cylindrical body 2 is formed larger than that of the other cylinder part and the outer diameter of the corresponding insertion body 3 is formed into a size corresponding to the inner diameter of the cylinder part and larger than that of the other part of the insertion body.