An actuator system for controlling a lumbar support includes a wire fixed and coupled with a lumbar support at one end; a driving motor rotatable in either the clockwise or counterclockwise direction; a worm coupled with the driving shaft of a driving motor; a deceleration part having a worm gear and a screw which decelerates the power of the driving motor; a slider connected to the other end of the wire, and having a protrusion portion and a spiral groove so as to carry out rectilinear reciprocating motion according to the rotation direction of the driving motor; and a housing inserted by the slider and having a wire-passing hole, a connection hole, a mounting hole and a guide hole, wherein the bending degree of a lumbar support may be automatically controlled by rotation driving force applied in a set range, thereby providing riding comfort to passengers.