To provide a manifold or a branch pipe including a plurality of pipes formed of two major assembling components whose structure or constitution is relatively simple, and facilitating the manufacture by blow molding.

This manifold is characterized in being composed of thermoplastic material, in particular, being provided by assembling at least the two prefabricated components 2 and 3, including a plurality of intake pipes 4 being formed along with the manifold or the branch pipe 1, at least partially, and preferably wholly, comprising each intake pipe 4 by the coaction between at least one walls 6 and 6' or 7 and 7' of at least one component 2 or 3 and an insert structure 8, attaching the insert 8 to the one component 2 or 3 before mutual assembling, and retaining it in a prescribed position between them after the assembling so as to form at least a part of the intake pipe 4 concerned.