PROBLEM TO BE SOLVED: To provide a hydraulic driving device of a work machine, which enables drive adjustment of a plurality of hydraulic actuators to be appropriately performed by the adjustment of an unload circuit.SOLUTION: The hydraulic driving device includes an unload circuit 103 for discharging pressure oil from a pressure oil supply path 26 for supplying pressure oil to the operation valve mechanisms 30 and 40 of a plurality of hydraulic actuators, and an operation valve 107 for adjusting the opening degree of the unload circuit 103. The hydraulic driving device further includes unload control means 150 for controlling the operation valve 107 based on detection information of operation detection means 151 and 152 and detection information of pump rotation detection means 153. The opening of the unload circuit 103 is adjusted according to the operation amounts of the operation valve mechanisms 30 and 40, the unload circuit 103 is adjusted to a small opening degree when the hydraulic pump is rotated at low speed, and the unload circuit 103 is adjusted to a large opening degree when the hydraulic pump is rotated at high speed.COPYRIGHT: (C)2013,JPO&INPIT【課題】アンロード回路の調節による複数の油圧アクチュエータの駆動調節を適切に行わせることができる作業機の油圧駆動装置を提供する。【解決手段】複数の油圧アクチュエータの操作弁機構30,40に圧油供給する圧油供給路26から圧油を排出するアンロード回路103、アンロード回路103を開度調節する操作弁107を設けてある。操作量検出手段151,152による検出情報、ポンプ回転検出手段153による検出情報に基いて操作弁107を制御するアンロード制御手段150を設け、操作弁機構30,40の操作量に応じてアンロード回路103を開度調節するように、油圧ポンプが低速回転であるとアンロード回路103を小開度に調節するように、油圧ポンプが高速回転であるとアンロード回路103を大開度に調節するように構成してある。【選択図】図5
