To provide a supporting structure of a cold-water/hot-water supply pipe, which enables the cold-water/hot-water supply pipe to be installed on the basis of design with a high degree of freedom, and which prevents the accumulation of water in a water sealing member by surely fixing the cold-water/hot-water supply pipe.

The hot-water supply pipe 23 and the cold-water supply pipe 24 are passed through a hole part 16a which is provided in a washing place-side floor 16, and a section between outer peripheral surfaces of the supply pipes 23 and 24 and a peripheral edge of the hole part 16a is closed with a cover member 26. In that state, a base part of a plate-like fixing bracket 28 is fixed to a wall surface part 16c by raising the supply pipes 23 and 24 on the floor 16, and the supply pipes 23 and 24 are fixed on the leading end side of the fixing bracket 28, so as to be fixed to the surface part 16c.