PURPOSE: To obviate the displacement or the like when shrinking is effected by heating, by providing a sheet section that has an aperture section at a position corresponding to a neck section of a rising section of a branch pipe and a shape to cover a main pipe, the undersurface of the part around the aperture section having an adhesive layer that exhibits a high shear strength at high temperatures.

CONSTITUTION: A heat-shrinkable sheet 1 has a sheet section 11 having an aperture section 12 at a position corresponding to a neck section 22 of a rising section of a branch pipe 21 and a shape capable of covering all the circumference of the main pipe 23, and the undersurface of the sheet section 11 has an adhesive layer 14 that exhibits a high shear strength at high temperature. The heat- shrinkable sheet 1 is put around the circumference of the main pipe 23 with the opposite sides of the sheet 1 overlapped and connected by a heat seal tape 3 and is heated to be shrunk. The part where the adhesive layer 14 is situated would not be displaced when the sheet 1 is heated and shrunk.