PURPOSE: To reduce the fraction defective for speaker production, by mounting and fixing an outside diaphragm to a bobbin under the state where a gauge is inserted into the bobbin and inserting an inside diaphragm into a coil bobbin to mount and fix it after pulling out the gause.

CONSTITUTION: A diaphragm is preliminarily divided into two, namely, an outside diaphragm 3a and an inside diaphragm 3b on basis of the diameter of a voice coil, and inside faces of the outside diaphragm 3a and a damper 8 are adhered to a voice coil bobbin 5 by an adhesive under the state where a voice coil gauge 7 is inserted between the voice coil bobbin 5 and a pole part 6'. After the adhesive is dried, the voice coil gauge 7 is pulled out from the coil bobbin 5, and the inside diaphragm 3b is inserted into the coil bobbin 5 and is adhered to the outside diaphragm 3a. In this case, since a thin foil 2 whose dimensions are matched to the outside diameter of the outside diaphragm 3a is stuck preliminarily to the upper face of the inside diaphragm 3b, the thin foil 2 is stuck to the upper face of the outside diaphragm 3a by an adhesive.