A lane keeping assist system, including: a first calculation unit which calculates left and right position errors of a front portion of the vehicle, a curvature of a lane of the front portion, and a head angle formed based on the lane from a front image of the vehicle captured by an image sensor, and calculates a target yaw rate using the left and right position errors, the curvature of the lane, and the head angle formed based on the lane which are calculated a second calculation unit which calculates a steering torque control value for driving the calculated target yaw rate using vehicle condition information including front and rear yaw rates of the vehicle sensed by a yaw rate sensor, and a steering angle and a speed of the vehicle and a steering driving unit which controls steering of the vehicle for keeping a lane.
