To provide piping in building of which the connection works can be easily carried out and of which the connection works to drain water implements can be simply carried out even when the installation positions of these implements are changed in the case of change of the installation positions when changing the layout or executing renewal works or the like.

Branch pipes 22 are connected to cross with a main pipe 21 at an angle of 45-60°. Branch joints 23 respectively provided with a widening faucet 26 at both ends of the primary pipe part 21 are connected so that the drain main pipe 24 and the primary pipe part 21 form a straight line through the faucet 26 in the drain main pipe 24 laid in a building and further, the main pipe can turn around the axial line of the primary pipe part 21 through a rubber ring 28 fitted in a circular groove 27 formed in the inner peripheral faces of the faucet or the outer peripheral face of the end of the drain main pipe. A horizontal drain pipe 25 connected to drain implements is connected to the branch pipes 22.