To shorten the time period for waiting for hot water in using terminal devices at the same time, while reducing the cost in a hot water supply piping system.

This hot water supply piping system A includes: a first main pipe 2 connected to a hot water supply device 1; a second main pipe 4a connected to the first main pipe 2 through a tees 10; a first branch pipe 3 connected to the first main pipe 2 through the tees 10, to which a water faucet 6a of a bathtub is connected; and a second branch pipe 5a connected to the second main pipe 4a through a tees 11, to which a water faucet 6b of the toilet is connected. The length Ya of the first branch pipe 3 is longer than that Yb of the second branch pipe 5a. The first branch pipe 3 has a base end part 3a connected to the tees 10, a bent part 3c bent from the base end 3a, and a forward end part 3b connecting the bent part 3c and the water faucet 6a of the bathtub. The length Za of the base end part 3a is shorter than that Zb of the forward end part 3b.