Abstract: In a muffler, a first exhaust outlet pipe has an opening-closing device, and a second exhaust outlet pipe is connected or joined to the first exhaust outlet pipe at a downstream portion of the opening-closing device. An overall length of the second exhaust outlet pipe is greater than the distance between the above joint portion, at which the second exhaust outlet pipe is connected to the first exhaust outlet pipe, and an exhaust inlet end of the first exhaust outlet pipe, and the overall length of the second exhaust outlet pipe is shorter than or generally equal to an overall length of the first exhaust outlet pipe. With this construction, in a low engine revolution speed range, the production of abnormal sounds in the second exhaust outlet pipe is prevented.