To provide a working machine capable of preventing an air cleaner and an upper plate part of a hood from being heated by heat of a DPF (Diesel Particulate Filter) muffler.

In the working machine, the DPF muffler 31 is arranged on the lateral side of an upper portion of an engine arranged on a moving machine body; the air cleaner is arranged on the lateral side, opposite to the engine, of the DPF muffler 31; and the hood for covering sections above the engine, the DPF muffler 31 and the air cleaner and sections on the lateral sides of them is provided. A heat-insulating cover 83 for covering the section above the DPF muffler 31 and the air cleaner-side lateral section thereof is attached to the DPF muffler 31. In addition, the heat-insulating cover 83 is separately provided with an upper cover 85 for covering the section above the section above the DPF muffler 31, and a lateral cover 86 for covering the lateral section, on the side of the air cleaner 33, of the DPF muffler 31.