PURPOSE: To produce a patterned-sheet diaphragm by press-contacting a patterned plate which has heated meshes onto the surface of a sheet such as a thermoplastic resin, softening the sheet to form uneven patterns on the sheet, and by shaping it with a mold into an acoustic diaphragm.

CONSTITUTION: A sheet C such as a thermoplastic resin is mounted on a female mold A, a press-contacting mold B is dropped, and a pattern plate B is press- contacted on the sheet C. A heat press-contact part B1 is heated up to the required temperature, thereby warming up a press-contact type B2, and forming uneven patterns corresponding to the unevenness of the pattern plate B2 on the sheet C surface, at the same time softening also the sheet C by warming it up. Where air inside a hollow A1 is extracted out of the female type A and the sheet C softened by this vacuum pressure is closely attached to the side wall of a hollow A1 of the female A and is shaped in the same form as the hollow A1. And by raising the pressing type B and taking out the sheet C, the mesh patterns corresponding to, for example, meshes of the pattern plate B2 are formed on the cone-shaped sheet C.