PURPOSE: To obtain a separator with a large discharge capacity and an excellent sealed reaction effect by binding and treating a mat-like member made of a mixture of glass fiber and cellulose fiber with acid resistant resin.

CONSTITUTION: A mat-like member made of a mixture of glass fiber and cellulose fiber bound and processed with acid resistant resin is used as a separator for a close-type lead storage battery constituted by impregnating a pole plate group stacked with a positive pole plate, a negative pole plate, and a separator with dilute sulfuric acid saving as an electrolyte. The glass fiber can be selected among those with a diameter of abou 0.5∼10μ, and the cellulose fiber can be selected among those which have many entangled fibers and a low apparent density when combed such as the linter pulp and others. The resin with excellent acid resistance and oxidiation resistance such as phenol resin, polyethylene resin, etc. is used for the acid resistant treatment.