In a muffler which includes an outer tube which configures an outer wall, an inner tube provided in the outer tube and having punching holes formed therein, and a sound absorbing material filled between the outer tube and the inner tube, and which is attached to an exhaust pipe for exhausting exhaust gas from an engine, the number of punching holes at portions of the inner tube which have a great length to the outer tube is set greater than the number of punching holes at portions of the inner tube which have a small length to the outer tube in comparison with the portions having the great length.