To prevent increase/decrease in pump flow rate due to load variation with change in the posture of a work attachment and improve the operability in arm pushing operation. A hydraulic excavator 1 with a front mechanism including an arm 33 driven by a hydraulic actuator 43 through operation of an operating lever 50 includes: first and second angle sensors 37 and 38 which detect the posture of the arm 33; and a controller 49 which, when the posture of the arm 33 is at a remoter side from an upperstructure 20 than a preset position and the position of a bucket 35 is adjusted from a maximum or nearly maximum preset operation amount of the operating lever 50 in arm pushing operation by the operating lever 50, changes the flow rate characteristic of pressure oil in relation to discharge pressure of a hydraulic pump 41 for supplying pressure oil to the hydraulic actuator 43, to characteristic PTS with a higher flow rate than flow rate characteristic PT at the time of operation with an operation amount other than the above operation amount, to drive the hydraulic pump 41.