A muffler of a motorcycle having an outside diameter greater than the outside diameter d1 of a rectilinear portion of a branch pipe is disposed at a transverse portion of an exhaust pipe. Since the muffler is formed to be roughly elliptic in sectional shape, the outside diameter of the muffler is represented by a major diameter da as the length in the direction of a major axis and a major diameter db as the length in the direction of a minor axis. When the muffler is disposed between a swing arm and a seat to be along the transverse portion of the exhaust pipe, the muffler can be disposed on the more vehicle front side while securing the capacity thereof. Therefore, protrusion of the muffler toward the rear of the vehicle is suppressed, and the external appearance of a vehicle rear portion is enhanced.