A hybrid excavator provided with an actuator impact reduction system, wherein the actuator impact reduction system comprises: an electric motor; a hydraulic pump-motor connected to the electric motor and configured to be driven in a forward or reverse direction; a hydraulic cylinder configured to be expanded and contracted by a hydraulic fluid that is supplied along first and second flow paths (13, 14) connected to the hydraulic pump-motor; first and second hydraulic valves (16, 17) installed in the first and second flow paths (13, 14) between the hydraulic pump-motor and the hydraulic cylinder, respectively, and configured to be shifted to control the first and second flow paths (13, 14) in response to a control signal applied thereto from the outside; characterized in that the hybrid excavator further comprises: a third hydraulic valve installed in a connection path connected to first and second branch flow paths (18, 19) that are branch-connected to the first and second flow paths (13a, 14a) on an upstream side of the first and second hydraulic valves (16, 17) and the first and second flow paths (13b, 14b) on a downstream side of the first and second hydraulic valves (16, 17), respectively, and configured to be shifted to compensate for or bypass a flow rate of the hydraulic fluid in order to overcome a difference in flow rate of the hydraulic fluid, which occurs due to a difference in cross section between a large chamber and a small chamber of the hydraulic cylinder; and first and second pilot chambers (31, 32) configured to supply a pressure of the first and second flow paths (13, 14) to the third hydraulic valve as a pilot signal pressure so as to shift the third hydraulic valve, the first and second pilot chambers (31, 32) being formed to have different cross sections. an electric motor; a hydraulic pump-motor connected to the electric motor and configured to be driven in a forward or reverse direction; a hydraulic cylinder configured to be expanded and contracted by a hydraulic fluid that is supplied along first and second flow paths (13, 14) connected to the hydraulic pump-motor; first and second hydraulic valves (16, 17) installed in the first and second flow paths (13, 14) between the hydraulic pump-motor and the hydraulic cylinder, respectively, and configured to be shifted to control the first and second flow paths (13, 14) in response to a control signal applied thereto from the outside; characterized in that the hybrid excavator further comprises: a third hydraulic valve installed in a connection path connected to first and second branch flow paths (18, 19) that are branch-connected to the first and second flow paths (13a, 14a) on an upstream side of the first and second hydraulic valves (16, 17) and the first and second flow paths (13b, 14b) on a downstream side of the first and second hydraulic valves (16, 17), respectively, and configured to be shifted to compensate for or bypass a flow rate of the hydraulic fluid in order to overcome a difference in flow rate of the hydraulic fluid, which occurs due to a difference in cross section between a large chamber and a small chamber of the hydraulic cylinder; and first and second pilot chambers (31, 32) configured to supply a pressure of the first and second flow paths (13, 14) to the third hydraulic valve as a pilot signal pressure so as to shift the third hydraulic valve, the first and second pilot chambers (31, 32) being formed to have different cross sections. a third hydraulic valve installed in a connection path connected to first and second branch flow paths (18, 19) that are branch-connected to the first and second flow paths (13a, 14a) on an upstream side of the first and second hydraulic valves (16, 17) and the first and second flow paths (13b, 14b) on a downstream side of the first and second hydraulic valves (16, 17), respectively, and configured to be shifted to compensate for or bypass a flow rate of the hydraulic fluid in order to overcome a difference in flow rate of the hydraulic fluid, which occurs due to a difference in cross section between a large chamber and a small chamber of the hydraulic cylinder; and first and second pilot chambers (31, 32) configured to supply a pressure of the first and second flow paths (13, 14) to the third hydraulic valve as a pilot signal pressure so as to shift the third hydraulic valve, the first and second pilot chambers (31, 32) being formed to have different cross sections.