A muffler includes a shell main that is formed in a cylinder with two openings opposite to each other being apart from each other in an axial direction of the shell main body by rolling a flat plate to have an overlapped portion overlapping an inner end portion and a shell portion, and a pair of end plates that are partially inserted in the openings of the shell main body and fixed to the shell main body. The inner end portion is formed with two cut-off portions at opening-side edges of the inner end portion, respectively, to avoid interference between the inner end portion and the end plates when the end plates are inserted into the openings of the shell main body.