A muffler is capable of sufficiently reducing flow noise, discharge noise,
vehicle noise, and cabin noise, preventing a pressure loss, and improving
output power. The muffler has a muffler body, an upstream pipe that opens
in the muffler body, and a downstream pipe that opens in the muffler
body. An opening is formed in a side wall of the downstream pipe in the
muffler body. The opening consists of many small holes arranged in an
elongated area extending in an axial direction of the downstream pipe.