To provide a muffler improving warming up performances of a catalyst, and improving control properties and travel stability of a vehicle through lowering height of a center of gravity and centralizing mass by arrangement of the catalyst.

A part of an exhaust gas passage until discharging exhaust gas into a muffler body 18A from an exhaust pipe 23 entering a muffler body 18A is bent and formed in a U-shape (U-shape type exhaust pipe 190), and the catalyst 187 is disposed at an upstream side of the U-shape type exhaust pipe 190. An exhaust pipe 191 straightly extending out from a downstream side of the U-shape type exhaust pipe 190 is extended to a first expansion chamber 183, and the catalyst 187 is disposed in the first expansion chamber 183. Consequently, the catalyst 187 is exposed to high temperature exhaust gas, and warming up performance of the catalyst 187 is improved. Since the catalyst 187 is disposed at height similar to an inlet part of the exhaust pipe 23 and the catalyst is disposed at a front section of the muffler body 18A, height of the center of gravity is lowered and mass is centralized.