A construction machine includes: a lower traveling body; an upper slewing body; a front attachment; a plurality of hydraulic actuators including traveling motors; hydraulic pumps; a plurality of control valves for the hydraulic actuators; a plurality of operation units for the control valves; traveling operation detectors that detect operations for the operation units for the traveling motors of the operation units; a back-pressure compensation valve generating back pressure in a return pipe line connecting each of the control valves and a tank and having a setting pressure switchable between low and high pressure setting values; and a back-pressure control section performing a back-pressure lowering control of making the setting pressure of the back-pressure compensation valve be the low pressure setting value when traveling operation amounts in the traveling operation units are large.