A hydraulic steering system (1) including a hydraulic steering unit (2) and an auxiliary device (3). Said The steering unit (2) feeds a hydraulic medium to a steering cylinder (5) according to the movement of a steering wheel (4). The auxiliary device (3) includes a valve unit (6) and also feeds a hydraulic medium to the steering cylinder (5) according to the movement of the steering wheel (4), in order to assist the steering movement. The hydraulic medium ejected or discharged from the steering cylinder (5) as a result of the hydraulic medium fed thereinto flows back into a tank (10) or to a pump (8, 9) through the steering unit (2).