A laminated porous film having a shutdown (SD) property and a high breakdown (BD) property combined includes at least two layers, which are a porous membrane layer (A layer) having a thickness of 10 μm or greater other than non-woven fabric and a non-woven fabric layer (B layer) having a fiber diameter of 1 μm or less. A value of the ratio (AP1/AP2) between air permeability when heating at a heating temperature of 150° C. to 200° C. for three minutes (AP1) and air permeability prior to heating (AP2) is 10 or greater at any heating temperature between 150° C. and 200° C.