To improve the productivity and the yield of materials when forming a sheet with a press 4 after applying embossing to a metallic sheet S such as a copper sheet and an aluminum sheet, for example.

The sheet S supplied from an uncoiler 1 is supplies to an embossing machine 3 through a leveler feeder 2, and embossed with embossing rolls 30, 31 while conveying it and sent out to the press 4 as it is. The embossing rolls 30, 31 are intermittently operated in synchronism with the operation of the press 4. By holding a portion of the sheet S with tension rolls 51, 52 arranged just before the embossing rolls 30, 31, required tension is imparted. A buffer space B for loosening a portion of the sheet S into a loop shape is provided under the shaft 1b of the uncoiler 1.