To economically form a filling member for a muffler and to simply attach it and to make its life longer by forming a previously fixed size of a loose bundle of thin pieces of a muffling material and assembling it so as to correspond to a shape of a filling member for the muffler to form a molded member, and fixing it as a molded body in a shape corresponding to the molded member.

In order to form and to process a filling member for a muffler, a loose bundle 16 having a specified quantity of muffling material (9) is formed. A cut piece 17 is formed from a covering material in parallel to the bundle 16 (10). The loose bundle 16 is then spread over the cut piece 17 (11) and the covering material is folded back to form a belt having an overhang 18 (12). The end edges of the belt are stitched together to form a member 19 having the overhang (13). The member 19 having the overhang is then wound centering around a winding center 20, and buried in the molded member 21 formed of two half pipes to form an assembly-shaped component (14). The overhang 18 is bonded to the covering material to form a cylindrical filling member 22 for the muffler (15).