visually confirmed at the opening 13 of the branch pipe installing groove 12 while the adhesive agent is filling the connection hole 5 39 from both end openings of the connector 2b as shown in fig1 the adhesive agent 6 poured into the hollow part 26 of the branch pipe passes through the hollow part 3b of the connector 2b and fills from the bottom part of connection hole 5a venting air to outside in a clearance between the outer surface of the connector 2b and the circumferential walls of the connection hole 5a in this case the surface of the connector 2b is formed with projections 23 for use in preventing channeling or short pass of the adhesive agent under an effect of buffer in the same manner as that of the preferred embodiment 1 so that the adhesive agent 6 is filled in the clearance with a scarce leakage in addition upon continuation of feeding of adhesive agent it can be visually confirmed that the adhesive agent 6 returns back while it is filling the clearance between the branch pipe 9b and the circumferential walls of the branch pipe installing groove 12 then the opening 13 of the branch pipe installing groove 12 is provided with a sealing processing by a plug and the like after curing of the adhesive agent 6 the holders such as the pipe supports and the like are removed if the holders are used as described above according to the.