A portable working machine is provided with a wheel guard partially covering a wheel rotated by a drive source such as an engine, and the wheel guard is retained by a retaining portion of an arm via rubber dampers serving as elastic members. Concave-convex portions are formed on the rubber dampers, a convex-concave portion corresponding to the concave-convex portions is formed in the wheel guard side, and the wheel guard is retained by the arm so that the concave-convex portions are engaged with the convex-concave portion.