PURPOSE: To provide lightness and sufficient strength and to improve productivity by providing an acid resistant synthetic resin in a lead or lead alloy sheet continuously and punching this sheet into a grid.

CONSTITUTION: A lead or lead alloy plate is formed by an extrusion process and is rolled out into a sheet 2 of the predetermined thickness. The sheet 2 is formed of lead-0.08% calcium alloy, and its width is set to 5mm constantly while its thickness is set to 0.7-0.9mm, for example. The thickness of a synthetic resin 1, which is varied according to the thickness of the sheet 2, is assigned to approximately 0.2 mm while the width is assigned to approximately 0.3 mm. The resin 1 is continued to the length direction of the sheet 2, and an area A contains no resin while an area B contains the resin. Then, the resin 1 is laminated on the sheet 2, and pressed and fitted so that the resin 1 is dispersed inside the sheet 2. Subsequently, the sheet 2 is formed into a grid by punching and the like, and a paste for a negative electrode is filled in the grid and is matured and dried. The area A is used for a lug 3 while the area B is used for a bridge 5 of the grid.