An axial-flow fluid machine comprising: a rotor having a plurality of blades, a casing which rotatably houses the rotor, a plurality of variable vanes annularly arranged around the rotor on the inside of the casing, and a variable vane drive device, the variable vane drive device comprising: a movable ring disposed at an outer circumferential side of the casing and having an annular shape; a plurality of five or less ring support mechanisms which are disposed at regular intervals along a circumferential direction of the movable ring and rotatably support the movable ring around the rotor; a rotary drive mechanism arranged to rotate the movable ring around the rotor; and a link mechanism which connects the movable ring to the variable vane such that an angle of the variable vane is varied by rotation of the movable ring, characterized in that each of the plurality of ring support mechanisms comprises: an inner roller disposed at an inner circumferential side of the movable ring; an outer roller which is disposed at an outer circumferential side of the movable ring, the movable ring being sandwiched between the inner roller and the outer roller; and a roller support base which rotatably supports the inner roller and the outer roller around an axis (Ai,Ao) parallel to the rotor in a state in which the movable ring is sandwiched between the inner roller and the outer roller and maintains contact therebetween. a rotor having a plurality of blades, a casing which rotatably houses the rotor, a plurality of variable vanes annularly arranged around the rotor on the inside of the casing, and a variable vane drive device, the variable vane drive device comprising: a movable ring disposed at an outer circumferential side of the casing and having an annular shape; a plurality of five or less ring support mechanisms which are disposed at regular intervals along a circumferential direction of the movable ring and rotatably support the movable ring around the rotor; a rotary drive mechanism arranged to rotate the movable ring around the rotor; and a link mechanism which connects the movable ring to the variable vane such that an angle of the variable vane is varied by rotation of the movable ring, characterized in that each of the plurality of ring support mechanisms comprises: an inner roller disposed at an inner circumferential side of the movable ring; an outer roller which is disposed at an outer circumferential side of the movable ring, the movable ring being sandwiched between the inner roller and the outer roller; and a roller support base which rotatably supports the inner roller and the outer roller around an axis (Ai,Ao) parallel to the rotor in a state in which the movable ring is sandwiched between the inner roller and the outer roller and maintains contact therebetween. a movable ring disposed at an outer circumferential side of the casing and having an annular shape; a plurality of five or less ring support mechanisms which are disposed at regular intervals along a circumferential direction of the movable ring and rotatably support the movable ring around the rotor; a rotary drive mechanism arranged to rotate the movable ring around the rotor; and a link mechanism which connects the movable ring to the variable vane such that an angle of the variable vane is varied by rotation of the movable ring, characterized in that each of the plurality of ring support mechanisms comprises: an inner roller disposed at an inner circumferential side of the movable ring; an outer roller which is disposed at an outer circumferential side of the movable ring, the movable ring being sandwiched between the inner roller and the outer roller; and a roller support base which rotatably supports the inner roller and the outer roller around an axis (Ai,Ao) parallel to the rotor in a state in which the movable ring is sandwiched between the inner roller and the outer roller and maintains contact therebetween. an inner roller disposed at an inner circumferential side of the movable ring; an outer roller which is disposed at an outer circumferential side of the movable ring, the movable ring being sandwiched between the inner roller and the outer roller; and a roller support base which rotatably supports the inner roller and the outer roller around an axis (Ai,Ao) parallel to the rotor in a state in which the movable ring is sandwiched between the inner roller and the outer roller and maintains contact therebetween.