To restrain the hang down of a center part when a duct is installed to the minimum while holding a telescopic property, crush pressure, pressure resistance and anti-negative pressure property as an original duct performance by making a coil a hollow body, in a telescopic duct consisting of a base material layer and a spiral reinforcement coil.

A telescopic duct 1 favorable as a duct for temporary piping is a telescopable and bellows shape cylinder and formed by a base material layer 2 and a spiral reinforcement coil 3. The base material layer 2 of this duct 1 is made of a resin film or a lamination of a base cloth and this, and the coil 3 is a hollow cylinder. As the manufacturing method of such a duct 1, for example, such a method that the telescopic duct 1 is obtained by winding the belt shape resin film or the lamination of the resin film and the base cloth and the hollow body on the plural rotation shafts of a pipe forming machine and fusing the belt shape resin film or the lamination in order is picked up.