A multilayer porous membrane comprising a porous membrane containing a polyolefin resin as a main component; and a porous layer containing an inorganic filler and a resin binder and laminated on at least one surface of the porous membrane; wherein the porous membrane has an average pore size d=0.035 to 0.060 μm, a tortuosity τa=1.1 to 1.7, and the number B of pores=100 to 500 pores/μm2, which are calculated by a gas-liquid method, and the porous membrane has a membrane thickness L=5 to 22 μm.