A swiveling work machine includes a traveling apparatus, a swivel base mounted on the traveling apparatus to be pivotable about a vertical axis, a hood disposed at a rear portion of the swivel base, the hood accommodating therein an engine, a support frame being disposed across over the engine, and a ROPS having a front end thereof fixed to the swivel base and a rear end thereof fixed to an upper portion of the support frame. The support frame includes a front leg member disposed on one lateral side of the ROPS, the front leg member extending to vicinity of a position forwardly of the swivel base.