PURPOSE: To prevent any separation of an active material and improve close contact between the active material and a separator so as to prevent any reduction in the discharge capacity of a sealed lead storage battery by subjecting mixture consisting of a polyolefin-system resin, a plasticizer and a filler to extrusion molding to obtain a sheet which is then pressed and fixed upon the surface of a positive plate, being followed by extracting the plasticizer so as to form minute holes in the sheet.

CONSTITUTION: Mixture consisting of polyethylene, pulverized silica and a plasticizer is extruded and molded into a sheet while heating and kneading the mixture by means of an extrusion molder. Before the sheet is cooled and solidified, it is superimposed on a positive plate. Then the sheet is cooled and solidified while pressure is applied with a roller presser thereby unifying the sheet and the positive plate. Next, the plasticizer is extracted with a solvent such as trichloroethylene so as to provide the sheet with minute holes thereby enabling it to work as a separator. Thus obtained positive plates are combined with negative plates so as to assemble a desired small sealed lead storage battery.