An fuel injection control unit (an electronic governor 12 and a controller 13) for an engine 1 is capable of performing control in a governor region based on an isochronous characteristic. A working machine controller 18 receives a delivery pressure signal P and controls a regulator 16 such that, when the delivery pressure of a hydraulic pump exceeds a predetermined pressure P1, the displacement of the hydraulic pump does not exceed a value decided in accordance with a preset pump absorption torque curve 20. Also, the working machine controller 18 controls the regulator 16 such that, when the delivery pressure of the hydraulic pump 2 is not higher than the predetermined pressure P1, the displacement of the hydraulic pump is increased as the delivery pressure of the hydraulic pump lowers from the predetermined pressure P1. As a result, even when the governor region is controlled based on the isochronous characteristic, the delivery flow rate of the hydraulic pump is increased as an engine load reduces.