In a variable vane drive device of an axial-flow fluid machine, a ring support unit supporting a movable ring includes: a first roller; a first support part supporting the first rollers so as to be relatively immovable with respect to a vane holding ring in a radial direction and in an axial direction; a second roller; a second support part supporting the second roller so as to be relatively movable with respect to the vane holding ring in the radial direction and pressing the second roller in the radial direction; a third roller allowing relative movement of the movable ring in the radial direction and restricting relative movement of the movable ring in the axial direction; and a third support part supporting the third roller so as to be relatively immovable with respect to the vane holding ring in the axial direction and in the radial direction.