To provide a steel-frame cutting apparatus for a shovel machine capable of maintaining an object to be cut in such a manner that the object always orthogonally crosses sliding surfaces of cutter blades when the cutter blade tips mesh, in the steel-frame cutting apparatus for a shovel machine used for a dismantlement or the like of a structural steelwork, and also capable of restraining generation of a clearance between the sliding surfaces of the cutter blades during cutting.

A pair of beaked turning arms are turnably pivoted on a holding frame having a cutter blade driving means, and the end surfaces opposed to each other of the arms are made to be cutter blades. An auxiliary arm is welded on either of the arms at slightly wider interval than the thickness of the turning arm. As a result, when the object to be cut like the steel frame is pinched by the auxiliary arm and the pair of the turning arms, the object is maintained in such a manner that it always orthogonally crosses the sliding surfaces of cutter blades. The generation of the clearance between the sliding surfaces of the cutter blades during cutting is also restrained.