To provide a device and a method for forming a lattice of an electrode plate stock capable of improving the productivity of a strip-like member having a lattice part, and preventing generation of any torsion of frame bones of the lattice part or generation of cracks in an end part of a slit.

In the device for forming the lattice of the electrode plate stock, a front projection 45, a center projection 46 and a rear projection 47 to hold the electrode plate stock 40 when forming the slit 43 are provided on a side surface 23 with the slit 43 formed in the electrode plate stock 40 which is a left fixed die 22 second from the left upper stream fixed die 22 out of a plurality of fixed dies 22 in right and left fixed die units.