<p>Provided is a porous polypropylene film that has both air permeability and piercing strength. It is possible to obtain a porous polypropylene film having an air permeability of 700 seconds/100 mL or less, a piercing strength of 1.5 N or greater, and ß activity by bringing the film tensile strength in the machine direction to EMD = 100 MPa or greater, the film tensile strength in the direction perpendicular to the machine direction to ETD = less than 100 MPa, and the ratio of EMD and ETD to EMD/ETD = 1.5 to 10.</p>
