An automatic bending machine produces a steel rule punching die to be used for forming predetermined notch lines or fold lines in a paper strip, a sheet, a board member, or the like in production of a paper container or a corrugated box. The automatic bending machine has a bending tool which bends a band blade into a predetermined shape. In the machine, a diamond grinder which is laterally and vertically moved by a computer control is disposed in front of the bending tool. When the bending tool is combined with the diamond grinder, bending of the band blade, linear cutting of the both ends, nicking of a blade edge, bridging (notching) of a blade bottom, and broaching (slotting) of a blade side wall are enabled.