Hydraulic drive device

A hydraulic drive device that drives a plurality of hydraulic devices including at least a first hydraulic device, a second hydraulic device, and a third hydraulic device by supplying a working fluid to each of the plurality of hydraulic devices, the hydraulic drive device comprising:

• a plurality of pumps including at least a first pump connected to the first hydraulic device and a second pump connected to the second hydraulic device;
• a merge passage that is connected to the plurality of pumps and in which streams of the working fluid discharged from the plurality of pumps join together;
• a flow rate control valve that is connected to the merge passage and the third hydraulic device and controls a flow rate of the working fluid flowing from the merge passage to the third hydraulic device by adjusting an opening degree of the flow rate control valve according to a flow rate control signal that is input to the flow rate control valve;
• and
• a pressure compensation valve that is provided on a side of the third hydraulic device relative to a merge point at which the streams of the working fluid join together in the merge passage and maintains an upstream-downstream pressure difference of the flow rate control valve at a predetermined pressure.