NOVELTY - A separator (3) has heat-resistant porous layer on at least one side of a resin porous membrane. The ratio of the resin in the total volume of the structural component of the separator is 50-99.9 vol.%. The heat-resistant porous layer contains heat-resistant microparticles, binder and expandable microparticles. The volume ratio of the expandable microparticles and heat-resistant microparticles is 10:90-95:5. The heat-resistant porous layer contains polymer including group having cyclic structure including amide bond and skeleton derived from polymerizable double bond as binder.    USE - Separator used for nonaqueous-electrolyte battery (claimed). Uses include but are not limited to for mobile telephone, notebook personal computer, electric vehicle, hybrid vehicle and electric tool.    ADVANTAGE - The separator has excellent heat resistance and reduced thickness. The nonaqueous-electrolyte battery containing separator has high reliability.    DETAILED DESCRIPTION - A separator has heat-resistant porous layer on at least one side of a resin porous membrane including polyolefin having melting temperature of 80-180 degrees C as a main component. The ratio of the resin in the total volume of the structural component of the separator is 50-99.9 vol.%. The heat-resistant porous layer contains heat-resistant microparticles, binder, and expandable microparticles which expanded in a nonaqueous electrolyte (4) and absorption quantity of non-aqueous electrolyte is increased by heating. The volume ratio of the expandable microparticles and heat-resistant microparticles is 10:90-95:5. The heat-resistant porous layer contains polymer as binder including group having cyclic structure including amide bond and skeleton derived from polymerizable double bond. The polymer has glass transition temperature of 130 degrees C or more and weight average molecular weight of 350000 or more. The content of the polymer is 0.1 parts mass or more with respect to total 100 parts mass of the expandable microparticles and heat-resistant microparticles. The thickness of the heat-resistant porous layer is 2-10 mu m. An INDEPENDENT CLAIM is included for nonaqueous-electrolyte battery, which has positive electrode (1), negative electrode (2), separator and nonaqueous electrolyte.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of the nonaqueous-electrolyte battery.    Positive electrode (1)    Negative electrode (2)    Separator (3)    Nonaqueous electrolyte (4)    Battery can (5)