The present invention relates to a hydraulic system for a construction machine, and more particularly, to a hydraulic system for a construction machine including a plurality of actuators. Each of the actuators has a pump/motor, is operated under a control of the corresponding pump/motor, and stores working oil in an accumulator thereof or receives the working oil supplemented from the accumulator in accordance with the difference between the flow rate introduced to the actuator and the flow rate discharged from the actuator.