Abstract: A method for plasma-treating a porous body, comprising the steps of generating plasma using an inert gas or a mixed gas of an inert gas and a reactive gas, (a) blowing the resultant plasma gas to the porous body at a flow rate per a unit area of the porous body of 0.002 to 2 L/minute/cm2, (b) sucking the porous body in a plasma gas atmosphere, or (c) sucking the porous body while blowing the plasma gas to the porous body at said flow rate, thereby treating the plasma the surfaces and pores of said porous body with plasma.

Abstract: A multi-layer, microporous polyolefin membrane having at least three layers, which comprises first microporous layers made of a polyethylene resin for constituting at least both surface layers, and at least one second microporous layer comprising a polyethylene resin and polypropylene and disposed between both surface layers, the heat of fusion (?Hm) of the polypropylene measured by differential scanning calorimetry being 90 J/g or more, and the polypropylene content in the second microporous layer being 50% or less by mass based on 100% by mass of the total of the polyethylene resin and the polypropylene.