To provide a die for manufacturing a polar plate of a wet charge battery capable of eliminating losses of a material, saving the manufacturing cost, preventing growth of burrs, improving the quality of the polar plate, simultaneously improving the productivity and the economy by producing products by a single die and in a single step, and changing the polar plate in a diamond mesh shape.

A polar plate of diamond mesh shape is formed on both sides by feeding a lead material wound in a coil. A plurality of pairs of forming blades (10, 10') are attached to a lower end along the feed line of the lead material by corresponding bolts (11, 11'). The pair of forming blades (10, 10') include an upper die (T) attached in a tapered shape so as to form successively narrower steps, and a lower die (L) having a bottom die (20) of the shape having successively narrower stepped parts attached thereto on the line to transfer the fed lead material (P) in a corresponding manner to the forming blades (10, 10').