A muffler has a casing with a plurality of sound-muffling chambers, exhaust pipes that pass through at least two sound-muffling chambers and to pass through exhaust from an engine, a plurality of apertures provided in each exhaust pipe, and a plurality of valves provided in each of the apertures. In this muffler, the plurality of apertures are provided at the locations at which an exhaust flow from one aperture and an exhaust flow from another aperture do not interfere with each other. When there are two apertures, the apertures are provided at positions in the exhaust pipes at which the apertures do not face each other. For this reason, by avoiding interference between exhaust flows from the two apertures, it is possible to suppress an abnormal sound caused by the interference.