A fuel supply pipe assembly according to at least one embodiment of the present disclosure is a fuel supply pipe assembly for supplying fuel to a fuel nozzle provided on a side portion of a combustion liner of a gas turbine combustor, provided with: a fuel supply pipe for supplying the fuel to the fuel nozzle; a first flange portion capable of coupling with a flange portion of a fuel line for supplying the fuel to the fuel supply pipe; and a second flange portion capable of coupling with a top hat portion of the gas turbine combustor. The first flange portion has a plurality of radially outward protrusions arranged at intervals in the circumferential direction, and a plurality of first bolt holes penetrating the first flange portion in the axial direction. The first bolt holes are formed at the same circumferential positions as the protrusions, respectively.