A method for producing a microporous thermoplastic resin membrane from a thermoplastic resin and a membrane-forming solvent, using as part of a starting material film waste based on the thermoplastic resin and the membrane-forming solvent, which is generated in the production process of the microporous thermoplastic resin membrane, comprising the steps of melt-blending a virgin thermoplastic resin and a membrane-forming solvent in an extruder to prepare a virgin material solution, adding the film waste generated in the same or different production processes to the virgin material solution in a molten state in the extruder at an intermediate point, melt-blending them to prepare a thermoplastic resin solution, extruding the thermoplastic resin solution through a die, cooling the extrudate to form a gel-like sheet, and removing the membrane-forming solvent from the gel-like sheet.