To provide a branch pipe without easily generating separation relating to a polyethylene resin-made branch pipe, providing a reinforcing layer able to obtain sufficient strength, and improving productivity.

In a branch pipe formed by welding work of a plurality of pipe units 2A, 2B, 2C constituting of polyethylene resin, in a peripheral surface 2a in a connection part of each pipe unit 2A, 2B, 2C, a reinforcing layer 5 consisting of reaction injection molding material of dicyclopentadiene or the like mainly composed of norbornene monomer and metathesis catalytic system is formed coating, and between peripheral surfaces 2a opposed of each pipe unit 2A, 2C, a rib part 6 is formed to the linked.