The disclosed invention relates to a swing control system for construction machines and is useful in a construction equipment in which the shaking or jerking movement of the upper swing structure due to the moment of inertia thereof is controlled by a simple electrical hydraulic control system so that although the swing manipulation is abruptly and repeatedly performed during the excavation or dumping operation, an operator can control the soft swing start/stop of the upper swing structure in the swing operation of construction machine, thereby improving manipulability and work efficiency of the work apparatus.