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.