A method for producing a microporous thermoplastic resin membrane comprising the steps of extruding a solution obtained by melt-blending a thermoplastic resin and a membrane-forming solvent through a die, cooling an extrudate to form a gel-like molding, removing the membrane-forming solvent from the gel-like molding by a washing solvent, and removing the washing solvent, the washing solvent having (a) a surface tension of 24 mN/m or less at a temperature of 25.degree. C., (b) a boiling point of 100.degree. C. or lower at the atmospheric pressure, and (c) a solubility of 600 ppm (on a mass basis) or less in water at a temperature of 16.degree. C.; and the washing solvent remaining in the washed molding being removed by using warm water.