To surely convey a sheet with a scrap by conveying a sheet before blanking to a blanking position by a conveying device in a state that the scrap blanked by a blanking die and the flexible sheet before blanking connected to the scrap are held by the conveying device.

A sheet 4 placed on a base 3 and a die 4 is blanked by a blanking die 2 to form a through hole 9. A conveying head 15 waiting before the die 2 is moved in the X direction and entered into the blanking die 2, covers the through hole 9, sucks the sheet 4 and a scrap 10 for lifting and conveying the same to a chute 8, and conveys the sheet 4 to be blanked, to an upper part of the die 6. Then the sheet 4 and the scrap 10 are opened, the sheet 4 is placed on the base 3 and the die 6, and the scrap is conveyed to an upper part of the chute 8. Then the scrap 10 is moved in the opposite direction until it is positioned on the upper part of the base 3, and these processes are repeated for continuously forming the through holes 9.