PURPOSE: To improve the accuracy of the posture of nozzle vanes and reduce a driving loss by making the pitch circle of a first rotating ring member the same as that of said nozzle vanes, and forming a parallelogrammatic four-node link mechanism with said nozzle vanes, levers, and a rotating ring.

CONSTITUTION: The first rotating ring member 32 which constitutes a rotating ring 28 is placed symmetrically with respect to the center line C of a pitch circle A on which the shafts of nozzle vanes 21 are placed in between. The end parts of the first rotating member 32 are connected to each other via the second ring member 33 which is rotatable centering around positions at which the pitch circle A is crossed with its center line C, and the first rotating ring member 32 is positioned outward to the positions in which the shafts of nozzle vanes 21 are placed. And, the nozzle vanes 21, levers 23, and rotating ring 28 form plural parallelogrammatic four-node links.