To provide a hydraulic driving device of a construction machine capable of suppressing the fluctuation of the moving speed of hydraulic actuators according to the variation of load pressure while reducing energy loss when driving the plurality of hydraulic actuators at the same time dividing the discharged oil of a hydraulic pump.

The control device 40 controls the torque needed for the rotation of a generator 65 or 66 corresponding to a low load cylinder in which load pressure is lower of the hydraulic cylinders 21, 22 using inverters 67 or 68 in the case the load pressures of the hydraulic cylinders 21, 22 (a plurality of hydraulic actuators) are detected by pressure sensors 71 to 74 and both the hydraulic cylinders 21, 22 are operated, the fluctuation of the differential pressure of the upstream and the downstream of a direction switching valve 24 or 25 is suppressed corresponding to the low load cylinder by raising the resistance of the rotation of the hydraulic motor 63 or 64 corresponding to the low load cylinder, a storage device 80 stores electric energy generated by the generator 65 or 66.