A battery separator is provided which is hardly broken by tension during the manufacture of batteries, is hardly punctured with a plate flash, and is hardly torn off with a plate edge, thereby hardly causing a short circuit. Accordingly, the separator can facilitate the stable manufacture of the batteries. The battery separator is equipped with a fiber sheet containing a polypropylene fiber having a tensile strength of not less than 10 g/d (denier) and a Young's modulus of not less than 800 kg/mm.sup.2, said separator having a resistance of not less than 585 gf to puncture by edge, or is equipped with a fiber sheet containing not less than 10 mass % of a polypropylene fiber having a tensile strength of not less than 10 g/d (denier) and a Young's modulus of not less than 800 kg/mm.sup.2.