A hydraulic circuit for a swivel working machine, in which the operation of the working unit is speeded up when the swiveling body and the working unit are simultaneously operated, includes, for this purpose, first and second operating valves (15.sub.1 and 15.sub.2) connecting the delivery conduit of a hydraulic pump (10) to a swiveling hydraulic motor (16.sub.1) and to a working unit cylinder (16.sub.2), and pressure compensating valves (18) provided between the first operating valve (15.sub.1) and the swiveling hydraulic motor (16.sub.1) and between the second operating valve (15.sub.2) and the working unit cylinder (16.sub.2), the load pressure of the swiveling hydraulic motor (16.sub.1) and the load pressure of the working unit cylinder (16.sub.2) being introduced into a load pressure introducing conduit (23) by way of check valves (42), the pressure compensating valves (18) being set by the load pressure of the load pressure introducing conduit (23), the check valve (42) for detecting the load pressure of the swiveling hydraulic motor (16.sub.1) being prevented from operating when the second operating valve (15.sub.2) is operated.