POROUS POLYPROPYLENE FILM

In order to provide a porous polypropylene film in which the ratio of change in air permeability is small and the initial air-permeating property is satisfactory even under high temperature environment, a porous polypropylene film is proposed, satisfying the following conditions (1) and (2) regarding air-permeability (Pa 1 ) at 20°C and air-permeability (Pa 2 ) after heating at 95°C for one hour: (1) The Pa 1 is 800 seconds/100 ml or less (2) The ratio of change in air permeability calculated by the formula below is 120% or less