<p>The operability when performing a combined arm-crowd and bucket operation can be improved. A hydraulic drive device for a hydraulic excavator includes: a bucket directional control valve 16 and a second arm directional control valve 18, which are connected in parallel tandem with a first hydraulic pump 11; a first arm directional control valve 21 that is connected to a second hydraulic pump 12; and a flow rate restriction device that restricts the flow rate of pressure oil supplied to the second arm directional control valve 18, during crowd operation of a bucket 6. This flow rate restriction device includes a variable throttle 30 whose opening is controlled so as to become smaller as a bucket operating device 28 is operated to the crowd side, the variable throttle 30 being provided in a bypass path 29a connecting to the supply port of the second arm directional control valve 18.</p>
