A muffler of a construction machine is formed by respectively coupling silencers to entrance and exit sides of an exhaust-gas purifying device by flanges. In flange coupling portions, mounting seats are provided integrally with lower semicircumferential portions of the flanges of the silencers in a manner such as to protrude toward outer peripheries of the flanges. By coupling the mounting seats to muffler mount brackets attached to a muffler mount, the muffler is mounted on the muffler mount.