An edger having a main frame, at least one front wheel fastened in the front portion of the main frame, two rear wheels fastened in the rear portion of the main frame, a rotary blade disposed in the front portion of either side of the main frame and capable of conducting edging, an engine mounted on the main frame and a driving device for operating the rotary blade with the engine, the edger comprising: a resin cover fastened to a circular flange on the rotary-blade supporting shaft for covering a portion of the rotary blade. A structure for fitting the rotary blade cover includes a thin metal plate having an outer diameter larger than the flange, and fastening members for clamping the inner portion of the cover between the flange and the thin metal plate. Bolt assemblies are provided for fastening the thin metal plate and the cover together at a position outside the flange.