PURPOSE: To enable to always perform an appropriate revolution, by a method wherein a hydraulic circuit of a hydraulic shovel is caused to receive a reduced shock produced at a revolution accelerating time and a decelerating time, a revolution circuit takes a precedence of other circuits at a time when a revolving operation and an arm and boom operation take place simultaneously.

CONSTITUTION: In the case of revolution, a lever 51 falls in an A-direction, and a pressure PiA, produced at a secondary side of a varibale pressure reducing valve 53a of a remote control valve 50, is led to an A1-direction. With a revolving switching valve 22 changed over, a discharge oil of a hydraulic pump P2 is led in an A2-direction, and is led to a revolving motor M3 through a counter balance valve 63 to perform a revolving acceleration. Then, if a switching valve 23 for arm is changed over, extra oil, bled off by a valve 40, is led in an A5-direction to flow to an arm cylinder. A discharge pressure of a hydraulic pump P2 flows, in priority, to a revolving circuit without being affected by a pressure of an arm circuit. At a time when a revolving acceleration and a boom lifting operation are simultaneously performed, a discharge oil of the hydraulic pump P2 is flowed to the revolving circuit, taking a precedence of others, by means of a variable sequence valve 40, and besides, extra oil flows from the valve to accelerate revolution.