To provide a drain collecting pipe which can be replaced without large-scaled operation, and a drain collecting pipe set.

The drain collecting pipe set includes the drain collecting pipe 1 and a fixing member 2. The drain collecting pipe includes an upper joining part 12 joined to a vertical pipe on an upper floor, a lower joining part 13 joined to a vertical pipe 5 through which drain is allowed to flow downward a floor slab, a pipe body 11 joining the upper joining part to the lower joining part. The pipe body includes a flange part 19 having a plurality of through-holes 20 enlarged in a direction orthogonal to the direction of the inside drain flow from the outer surface of the pipe body and penetrated in the same direction as the drain flow. The fixing member includes a storage part 27 for storing part of the drain collecting pipe including the lower joining part, and a tubular joining part 28 for communicating with the storage part. The fixing member is formed so as to allow the lower joining part to be communicated with the joining part when the lower joining part is stored in the storage member.