An adjustable guide apparatus for a turbine, comprising a bearing ring with a plurality of guide vanes, wherein the guide vanes are rotatably mounted on the bearing ring with the aid of guide vane shafts, wherein in order to position the guide vane, the guide vane shaft is allocated an adjusting lever which engages in a rotatable rotating ring of the adjustable guide apparatus, and wherein, in order to be held in an exhaust gas guiding section of the turbine, the adjustable guide apparatus has a support ring, and wherein the support ring serves to mount the rotating ring. The rotating ring is radially and/or axially guided with the aid of at least one guiding element, wherein the guiding element is received on the support ring. Furthermore, the invention relates to a turbine with an adjustable guide apparatus and to an exhaust turbocharger.