To assure water-tightness of pipe pathway by securely closing a connected part between a branching pipe joint and a pipe regardless of installing environment when a branching pipe is connected to branch to a rib pipe.

The branching pipe joint is formed to include an saddle section and a branching section. The saddle section comprises an upper saddle part which adjoins to hemihedry of outer periphery of a rib pipe and a lower saddle part which is opposed to the upper saddle part and adjoins to other hemihedry of the outer periphery of the rib pipe. The branching section is integrally provided on the upper saddle part or the lower saddle part and is connected to the branching pipe. This is fixed to the rib pipe via a packing between opening periphery formed on a pipe wall of the rib pipe and inside surface of the saddle section covered on the opening periphery. The packing is formed to be such profile that the rib pipe side of the joint is coincided with outline of the rib pipe and the saddle section side of the joint is coincided with inner form of the saddle section.