Abstract: Provided is a slewing-type hydraulic work machine including a boom raising working pressure detection unit that detects boom raising working pressure, and a capacity control device that controls a slewing motor capacity during a slewing and boom-raising operation and performs detecting an actual slewing distribution factor correspondence value corresponding to a ratio of energy distributed to a slewing motor to energy of discharged hydraulic oil, setting a boundary value of the actual slewing distribution factor correspondence value to limit the ratio more with increase in boom raising working pressure, and a capacity operation of making the slewing motor capacity higher than a limit capacity within a slewing priority allowable period until the actual slewing distribution factor correspondence value reaches the boundary value during the slewing and boom-raising operation and limiting the slewing motor capacity to the limit capacity or less after the slewing priority allowable period.