An aircraft gas turbine comprising: a rotor configured to rotate around an axis (Am) ; a rotor blade having a rotor blade main body extending radially outward from the rotor , a rotor blade shroud provided at a tip of the rotor blade main body , and a fin projecting from an outer peripheral surface of the rotor blade shroud ; a casing surrounding the rotor and the rotor blade from an outer periphery side and forming a gap with the fin ; a stationary blade having a stationary blade shroud and a stationary blade main body extending radially inward from the stationary blade shroud , the stationary blade shroud fixed to the casing on a downstream side of the rotor blade such that a cavity (Ct) is formed by at least the stationary blade shroud , the rotor blade shroud and the fin ; and a guide member (53;153) provided in the cavity (Ct) and extending inward from a radial outer side (Dro), an inner-side end part (53a;153a) of the guide member (53;153) on a radial inner side (Dri) facing the outer peripheral surface of the rotor blade shroud with a gap therebetween, wherein the outer peripheral surface of the rotor blade shroud facing the inner-side end part (53a;153a) of the guide member (53;153) is formed in parallel with the axis (Am), characterized in that the guide member (53;153) is provided with an inclined portion (54;154) which is inclined radially outward from the inner-side end part (53a;153a) of the guide member (53;153) so as to approach the stationary blade in a downstream direction in which the axis (Am) extends, and wherein the inner-side end part (53a;153a) of the guide member (53;153) is disposed closer to the axis (Am) in the radial direction than an inner peripheral surface of the stationary blade shroud . a rotor configured to rotate around an axis (Am) ; a rotor blade having a rotor blade main body extending radially outward from the rotor , a rotor blade shroud provided at a tip of the rotor blade main body , and a fin projecting from an outer peripheral surface of the rotor blade shroud ; a casing surrounding the rotor and the rotor blade from an outer periphery side and forming a gap with the fin ; a stationary blade having a stationary blade shroud and a stationary blade main body extending radially inward from the stationary blade shroud , the stationary blade shroud fixed to the casing on a downstream side of the rotor blade such that a cavity (Ct) is formed by at least the stationary blade shroud , the rotor blade shroud and the fin ; and a guide member (53;153) provided in the cavity (Ct) and extending inward from a radial outer side (Dro), an inner-side end part (53a;153a) of the guide member (53;153) on a radial inner side (Dri) facing the outer peripheral surface of the rotor blade shroud with a gap therebetween, wherein the outer peripheral surface of the rotor blade shroud facing the inner-side end part (53a;153a) of the guide member (53;153) is formed in parallel with the axis (Am), characterized in that the guide member (53;153) is provided with an inclined portion (54;154) which is inclined radially outward from the inner-side end part (53a;153a) of the guide member (53;153) so as to approach the stationary blade in a downstream direction in which the axis (Am) extends, and wherein the inner-side end part (53a;153a) of the guide member (53;153) is disposed closer to the axis (Am) in the radial direction than an inner peripheral surface of the stationary blade shroud . <EOS>