<p>A muffler (10) of an engine blower as a working machine includes a muffler body (11) and a diffuser (15) covering an exhaust gas exhaust opening (13) arranged on the muffler body (11). The diffuser (15) has a diffusion space for diffusing an exhaust gas and an exhaust plane (31) where a plurality of exhaust circular holes (33) are formed for exhausting the diffused exhaust gas outside. The opening ratio obtained by the exhaust holes (33) with respect to the exhaust plane (31) is gradually increased from the portion corresponding to the exhaust opening (13) toward the external circumferential side.</p>
