To provide a method for lining a branched pipeline in which lining material is turned over and inserted into the branched pipeline without necessitating a special cut-off process and lining material is cured and simultaneously a flange and the inner surface of a main pipe are sealed and infiltration of fluid is prevented.

One end part of the body of cylindrical lining material impregnated with setting resin liquid is folded back to the outside. A flange 19 is formed on a cylindrical face comformable to the shape of the inner face of the main pipe of a pipeline in the end of a folded part. The lining material 14 provided with the flange 19 is positioned in the branched part of the pipeline and the flange 19 is stuck to the inner face of the main pipe in the circumferential edge. The body of the lining material is inserted into the branched pipeline and also pressed in contact therewith while allowing pressure of fluid to act on the inside of the folded part and turning over the body of lining material. The body of lining material is bonded to the branched pipeline and lined by curing setting resin liquid. In the lining method, a sealant 29 is applied to the boundary part of the folded part and the flange 19 and setting resin liquid is cured and also the sealant 29 is vulcanized.