PURPOSE: To effectively connect integrally a lining material of a main pipe and that of a branch pipe even if there is invasion water such as underground water, etc., by cutting OFF waters of the main and branch pipe before the main pipe is lined.

CONSTITUTION: Start liners 3, 4 are hydraulically inverted and inserted into main and branch pipes 1, 2 to cut OFF waters. The liner 3 is formed by impregnating flexible tubular nonwoven fabric 6 such as polyester, polypropylene, acryl, etc., covered with plastic film 5 having highly hermetical sealability on an outer surface with water cutoff agent 7. As a material of the film 5, polyurethane, polyethylene, etc., is selected. The agent 7 is substance cured in contact with water, and includes, for example, hydrophilic polyurethane resin, silicone resin, etc.