The invention relates to an adjustment device (1) for adjusting the height position of the hopper (2) for a livestock feeder, particularly applicable to a livestock weaning feeder, of the type comprising a post (3) on which a sleeve (4) for supporting the hopper is assembled with longitudinal sliding capacity. Said post comprises an outer screw thread (5) on which a displacement ring (6) is coupled by screwing, provided with a corresponding inner screw thread (7). The ring is in turn provided with a lower tubular portion (8) having an open cross-section, provided with an inner annular groove (9) in which a projecting outer flange (10) of the sleeve for supporting the hopper is inserted, being suspended from the ring, whereby when the ring is displaced downwards or upwards by screwing it on or unscrewing it from the post, it drives the sleeve in its movement.
