NOVELTY - A heat resistant microporous film has an olefin resin microporous film containing a micro hole and formed by uniaxially stretching an olefin type resin film, and a film which contains polymer of polymeric compound having 2 or more radically polymerizable functional groups in a molecule, formed on one or more portion of surface of the olefin resin microporous film. The heat resistant microporous film has preset thermal contraction rate at preset condition.    USE - Heat resistant microporous film used for separator for non-aqueous-electrolyte secondary battery (all claimed) e.g. lithium ion secondary battery.    ADVANTAGE - The microporous film has improved absorptivity of electrolyte solution and heat resistance, and improves discharge capacity and durability of non-aqueous-electrolyte secondary battery.    DETAILED DESCRIPTION - A heat resistant microporous film has an olefin resin microporous film formed by uniaxially stretching an olefin type resin film and containing a micro hole, and film which contains polymer of the polymeric compound which has 2 or more radically polymerizable functional groups in a molecule, formed on one or more portion of surface of the olefin resin microporous film. The sucking height of the dimethyl carbonate of one end portion set in a direction orthogonal to the stretching direction of the heat resistant microporous film during immersion in dimethyl carbonate for 30 minutes is 7 mm or more. The maximum thermal contraction rate of the heat resistant microporous film during heating from 25 degrees C to 180 degrees C at temperature increase rate of 5 degrees C/minute is 25% or less. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of heat resistant microporous film;    (2) battery separator; and    (3) non-aqueous-electrolyte secondary battery.    DESCRIPTION OF DRAWING(S) - The drawing shows the side view of the manufacturing apparatus used for extrusion process and conveyance process of microporous film.    Extruder (1)    T-die (2)    Extrusion opening (2a)    Cooling rollers (3,4)    Propylene-based resin film (A)