A porous multi-layer film, comprising: a first layer having a porosity of 30 to 60% and an average pore diameter of 0.01 to 0.1 μm and a second layer adjacent to the first layer, the second layer having a porosity of 50 to 80% and having pores with a pore average plane diameter of 0.1 to 50 μm of 70% or more on the basis of the area of the entire pores of the second layer, wherein porosity is measured as described in paragraphs - of the description; wherein the second layer has a thickness of 3 μm or more and occupies 30 to 70% of the entire thickness of the porous multi-layer film; and the porous multi-layer film has a thickness of 9 to 50 μm, a loop stiffness to the machine direction of 0.008 mg/μm or more when measured as described in paragraph of the description, a puncture strength of 0.15 N/μm or more when measured as described in paragraph of the description, a permeability of 1.5 x 10-5Darcy or more when measured as described in paragraphs - of the description, a shut-down temperature of 140°C or less when measured as described in paragraph of the description, a melt fracture temperature of 170°C or more when measured as described in paragraph of the description, a maximum shrinkage to a transverse direction of 25% or less in Thermomechanical Analysis under a load of 1mN/(1μm x 6mm) when measured as described in paragraphs - of the description, and a melt-down temperature (temperature that the length reaches 120%) of 160°C or more in Thermomechanical Analysis under a load of 1mN/(1μm x 6mm) when measured as described in paragraphs - of the description, wherein the second layer is prepared to contain a general heat-resistant resin of 50 volume% or more of a resin composition and contain inorganic materials of 30 to 60 wt% together, and the general heat-resistant resin has a melting temperature of 160 to 180°C, or is prepared to contain a high heat-resistant resin having a melting temperature of 180°C or more of 50 volume% or more of a resin composition, and other resin of 15 to 50 volume % of the resin composition to be liquid-liquid phase separated from the high heat-resistant resin. a first layer having a porosity of 30 to 60% and an average pore diameter of 0.01 to 0.1 μm and a second layer adjacent to the first layer, the second layer having a porosity of 50 to 80% and having pores with a pore average plane diameter of 0.1 to 50 μm of 70% or more on the basis of the area of the entire pores of the second layer, wherein porosity is measured as described in paragraphs - of the description; wherein the second layer has a thickness of 3 μm or more and occupies 30 to 70% of the entire thickness of the porous multi-layer film; and the porous multi-layer film has a thickness of 9 to 50 μm, a loop stiffness to the machine direction of 0.008 mg/μm or more when measured as described in paragraph of the description, a puncture strength of 0.15 N/μm or more when measured as described in paragraph of the description, a permeability of 1.5 x 10-5Darcy or more when measured as described in paragraphs - of the description, a shut-down temperature of 140°C or less when measured as described in paragraph of the description, a melt fracture temperature of 170°C or more when measured as described in paragraph of the description, a maximum shrinkage to a transverse direction of 25% or less in Thermomechanical Analysis under a load of 1mN/(1μm x 6mm) when measured as described in paragraphs - of the description, and a melt-down temperature (temperature that the length reaches 120%) of 160°C or more in Thermomechanical Analysis under a load of 1mN/(1μm x 6mm) when measured as described in paragraphs - of the description, wherein the second layer is prepared to contain a general heat-resistant resin of 50 volume% or more of a resin composition and contain inorganic materials of 30 to 60 wt% together, and the general heat-resistant resin has a melting temperature of 160 to 180°C, or is prepared to contain a high heat-resistant resin having a melting temperature of 180°C or more of 50 volume% or more of a resin composition, and other resin of 15 to 50 volume % of the resin composition to be liquid-liquid phase separated from the high heat-resistant resin.