A combustor comprising: a combustor main body comprising a transition piece that defines a flow channel therein, and a combustor basket inserted in the transition piece from an upstream side of the flow channel that sends, in operation, a combustion gas through the flow channel and defines a gap, through which a film air is sent, with an inner peripheral surface of the transition piece; a connecting portion which includes a connecting pipe fixed to a connection hole and which connects to the combustor main body from an outer peripheral side and communicates with the flow channel, wherein the connection hole is provided on an outer wall of the transition piece and protrudes outward from an outer peripheral surface of the transition piece and forms an interface portion where the inner peripheral surface of the transition piece and the connection hole are connected, wherein the interface portion is disposed such that it can be reached by the film air sent from the gap, and wherein the connecting portion includes an intake hole that connects an inside and outside of the connecting portion and is provided on a wall of the connection hole on a downstream side of the flow channel; and a flow guide disposed in the flow channel on the downstream side of the connecting portion so as to guide a compressed air introduced from outside the connecting portion through the intake hole to the flow channel on the downstream side of the connecting portion as film air, wherein the flow guide includes an introduction portion which is disposed proximal to the connecting pipe and extends from the intake hole toward the flow channel, and a flow guide main body portion which is connected to the introduction portion, extends toward the downstream side of the flow channel, and has a sector-like shape that gradually increases in dimension in a circumferential direction toward the downstream side of the flow channel. a combustor main body comprising a transition piece that defines a flow channel therein, and a combustor basket inserted in the transition piece from an upstream side of the flow channel that sends, in operation, a combustion gas through the flow channel and defines a gap, through which a film air is sent, with an inner peripheral surface of the transition piece; a connecting portion which includes a connecting pipe fixed to a connection hole and which connects to the combustor main body from an outer peripheral side and communicates with the flow channel, wherein the connection hole is provided on an outer wall of the transition piece and protrudes outward from an outer peripheral surface of the transition piece and forms an interface portion where the inner peripheral surface of the transition piece and the connection hole are connected, wherein the interface portion is disposed such that it can be reached by the film air sent from the gap, and wherein the connecting portion includes an intake hole that connects an inside and outside of the connecting portion and is provided on a wall of the connection hole on a downstream side of the flow channel; and a flow guide disposed in the flow channel on the downstream side of the connecting portion so as to guide a compressed air introduced from outside the connecting portion through the intake hole to the flow channel on the downstream side of the connecting portion as film air, wherein the flow guide includes an introduction portion which is disposed proximal to the connecting pipe and extends from the intake hole toward the flow channel, and a flow guide main body portion which is connected to the introduction portion, extends toward the downstream side of the flow channel, and has a sector-like shape that gradually increases in dimension in a circumferential direction toward the downstream side of the flow channel.