A hydraulic drive apparatus for hydraulically actuating a load, the hydraulic drive apparatus comprising: a hydraulic actuator which is connected to the load and is operated so as to actuate the load; a hydraulic pump configured to discharge hydraulic fluid and having a variable flow rate, the hydraulic pump being connected to the hydraulic actuator so as to configure a closed circuit in which hydraulic fluid discharged from the hydraulic pump is supplied to the hydraulic actuator and hydraulic fluid discharged from the hydraulic actuator is returned to a suction side of the hydraulic pump; a drive source which drives the hydraulic pump to cause the hydraulic pump to discharge hydraulic fluid; a charge circuit which feeds supplemental hydraulic fluid to the closed circuit when a pressure in the closed circuit is lower than a predetermined set pressure; an accumulator connected to the closed circuit so as to be able to receive hydraulic fluid discharged from the hydraulic actuator during a lowering drive in which the hydraulic actuator is operated so as to actuate the load in a lowering direction including a component of a direction in which gravity acts on the load; an accumulator-flow-rate regulator (44; 70) interposed between the closed circuit and the accumulator to change a flow rate of hydraulic fluid from the closed circuit to the accumulator; a regeneration actuator which is driven by energy of hydraulic fluid accumulated by the accumulator to convert the energy into motive power; a regeneration selector valve interposed between the accumulator and the regeneration actuator, the regeneration selector valve being switchable between a position for allowing hydraulic fluid to be supplied from the accumulator to the regeneration actuator and a position for cutting off the supply; a pump control section which limits the discharge flow rate of the hydraulic pump to a predetermined regeneration flow rate during the lowering drive; and a speed control section which operates the accumulator-flow-rate regulator (44; 70) so as to bring an actuating speed of the hydraulic actuator close to a target speed during the lowering drive, characterized in that the speed control section operates the accumulator-flow-rate regulator (44; 70) so as to bring an accumulator introduction flow rate close to a target introducing flow rate, the accumulator introduction flow rate being a flow rate of hydraulic fluid introduced from the hydraulic actuator to the accumulator, the target introducing flow rate being a difference between a target discharge flow rate which is a flow rate of the discharged hydraulic fluid corresponding to the target speed and a pump absorption volume equivalent to the regeneration displacement volume of the hydraulic pump. a hydraulic actuator which is connected to the load and is operated so as to actuate the load; a hydraulic pump configured to discharge hydraulic fluid and having a variable flow rate, the hydraulic pump being connected to the hydraulic actuator so as to configure a closed circuit in which hydraulic fluid discharged from the hydraulic pump is supplied to the hydraulic actuator and hydraulic fluid discharged from the hydraulic actuator is returned to a suction side of the hydraulic pump; a drive source which drives the hydraulic pump to cause the hydraulic pump to discharge hydraulic fluid; a charge circuit which feeds supplemental hydraulic fluid to the closed circuit when a pressure in the closed circuit is lower than a predetermined set pressure; an accumulator connected to the closed circuit so as to be able to receive hydraulic fluid discharged from the hydraulic actuator during a lowering drive in which the hydraulic actuator is operated so as to actuate the load in a lowering direction including a component of a direction in which gravity acts on the load; an accumulator-flow-rate regulator (44; 70) interposed between the closed circuit and the accumulator to change a flow rate of hydraulic fluid from the closed circuit to the accumulator; a regeneration actuator which is driven by energy of hydraulic fluid accumulated by the accumulator to convert the energy into motive power; a regeneration selector valve interposed between the accumulator and the regeneration actuator, the regeneration selector valve being switchable between a position for allowing hydraulic fluid to be supplied from the accumulator to the regeneration actuator and a position for cutting off the supply; a pump control section which limits the discharge flow rate of the hydraulic pump to a predetermined regeneration flow rate during the lowering drive; and a speed control section which operates the accumulator-flow-rate regulator (44; 70) so as to bring an actuating speed of the hydraulic actuator close to a target speed during the lowering drive, characterized in that the speed control section operates the accumulator-flow-rate regulator (44; 70) so as to bring an accumulator introduction flow rate close to a target introducing flow rate, the accumulator introduction flow rate being a flow rate of hydraulic fluid introduced from the hydraulic actuator to the accumulator, the target introducing flow rate being a difference between a target discharge flow rate which is a flow rate of the discharged hydraulic fluid corresponding to the target speed and a pump absorption volume equivalent to the regeneration displacement volume of the hydraulic pump.