Gas turbine combustor tail tube cooling structure is improved so that temperature distribution along tail tube axial direction is made gentle and large thermal stress is prevented from occurring resulting in enhancement of safety and reliability of the combustor tail tube. Supply jacket (16) is disposed between upstream side discharge jacket (14) and downstream side discharge jacket (15). The upstream side discharge jacket (14) is disposed apart from tail tube inlet (2) at position close to by-pass passage (10) so as to form non-cooled zone (A) in the vicinity of the tail tube inlet (2). On the downstream side thereof, the supply jacket (16) is disposed at position in tail tube (1) contracting portion and near the downstream side discharge jacket (15) so as to shorten length of cooling pipes there. <IMAGE>
