Provided is a lithium secondary battery separator including a laminate of a substrate and a porous heat-resistant polyimide film which covers at least one surface of the substrate. The porous heat-resistant polyimide film has pores which are regularly arrayed three-dimensionally and a film thickness of 5-20 μm. Penetration damage to the separator by growth of dendrite-shaped lithium is avoided, and it is also possible to meet a request which is demanded of the lithium secondary battery separator.