A gas turbine combustor includes a tubular combustion liner that has a plurality of dilution holes disposed circumferentially at a section downstream in a direction of flow of combustion gas, a combustor casing that encloses the combustion liner, a liner flow sleeve disposed between the combustion liner and the combustor casing, to define with the combustion liner an air flow path through which compressed air flows, the liner flow sleeve having a plurality of steam injection holes, and a steam distribution mechanism disposed on an outer peripheral side of the liner flow sleeve. The steam distribution mechanism distributes received injection steam to the steam injection holes. At least some of the steam injection holes are disposed so to face at least some of the dilution holes. The steam injection holes facing the respective dilution holes are each formed so as to spurt the injection steam toward the corresponding dilution hole.