To provide a remaking method for an existing conduit which can line the inner surface of the existing conduit having an intermittent part with a pipe liner having shape recoverability.

This remaking method for an existing conduit is to line the inner surface of the existing conduit 2 having an intermittent part with a thermoplastic resin made pipe liner 1. Using a liner deformed so that its cross section outline area is reduced in a condition that shape recoverability performance is added to a cylindrical body at a shape memory temperature as the pipe liner 1, the pipe liner 1 is inserted into the existing conduit 2. In addition, the method consists of a process for installing the pipe liner 1 on the intermittent part of the existing conduit 2, a process for covering a split cylinder shaped body 3 for controlling outline over the outside of the pipe liner 1 on the intermittent part of the existing conduit 2, a process for heating the pipe liner 1 from inside up to the shape memory temperature to recover the conduit to substantially original cylinder body, and a subsequent process for expanding the cylinder body 1' by air pressurization from inside in a preheating condition, adhering it to the inner surfaces of the existing conduit 2 and the split cylinder shaped body 3 for controlling outline, and then air-cooling it.