SEPARATOR FOR BATTERIES

A battery separator includes a polyolefin porous membrane; and a heat-resistant porous layer provided thereon, wherein the heat-resistant porous layer contains barium sulfate particles and an organic synthetic resin component, the barium sulfate particles contain 20% by volume or less of particles having a diameter of 0.5 μm or less and 10% by volume or less of particles having a diameter of 3.0 μm or more, the heat-resistant porous layer contains 70% by volume or more and 98% by volume or less of the barium sulfate particles when the total of the barium sulfate particles and the organic synthetic resin component is taken as 100% by volume, an average thickness of the heat-resistant porous layer is 2 μm or more and 10 μm or less, a moisture ratio of the separator is 400 ppm or less, and a content of hydrogen sulfide is 0.2×10mg/mor less.