An engine lug-down suppressing device for hydraulic work machinery(l), provided on the hydraulic work machinery including: an engine; a variable displacement hydraulic pump that is driven by the engine; a hydraulic actuator that is driven by discharge oil of the variable displacement hydraulic pump; operation instruction means for giving an instruction to cause the hydraulic actuator to operate; and target engine rotational speed instruction means for giving an instruction on a target engine rotational speed of the engine, the engine lug-down suppressing device comprising: detection means (51, 55) for detecting the presence or absence of an instruction by the operation instruction means; and pump absorption torque control means (54, 55) for controlling pump absorption torque of the variable displacement hydraulic pump in accordance with a detection result by the detection means, wherein the pump absorption torque control means is set to serve as: first control means for controlling pump absorption torque in accordance with the target engine rotational speed when no instruction is detected by the detection means; and second control means for controlling pump absorption torque in accordance with the target engine rotational speed when an instruction is detected by the detection means, and wherein the pump absorption torque determined by the first control means falls within a range equal to or smaller than the pump absorption torque determined by the second control means in an entire range of the target engine rotational speed, and characterized in that the pump absorption torque determined by the first control means is set to approach the maximum pump absorption torque (T2max) determined by the second control means with an increase in the target engine rotational speed, within a range of the target engine rotational speed included in the range in which the maximum pump absorption torque (T2max) determined by the second control means is obtained. detection means (51, 55) for detecting the presence or absence of an instruction by the operation instruction means; and pump absorption torque control means (54, 55) for controlling pump absorption torque of the variable displacement hydraulic pump in accordance with a detection result by the detection means, wherein the pump absorption torque control means is set to serve as: first control means for controlling pump absorption torque in accordance with the target engine rotational speed when no instruction is detected by the detection means; and second control means for controlling pump absorption torque in accordance with the target engine rotational speed when an instruction is detected by the detection means, and wherein the pump absorption torque determined by the first control means falls within a range equal to or smaller than the pump absorption torque determined by the second control means in an entire range of the target engine rotational speed, and characterized in that the pump absorption torque determined by the first control means is set to approach the maximum pump absorption torque (T2max) determined by the second control means with an increase in the target engine rotational speed, within a range of the target engine rotational speed included in the range in which the maximum pump absorption torque (T2max) determined by the second control means is obtained.