PURPOSE: To obtain the subject film consisting of a drawing type porous film made porous by drawing a non-porous film and a porous film formed from the non-porous film by physical boring other than drawing and having high strength and good moisture permeability, water proof property and windbreak property.

CONSTITUTION: A composition obtained by blending a linear low density polyethylene resin with a calcium carbonate filler and butadiene rubber is subjected to extrusion molding with a T die extruder to form a non-porous film, which is then drawn in the monoaxial direction at 80°C to provide a drawing type porous film. On the other hand, the non-porous film is pressed through a pair of nipping rollers in which either one roller is coated with fine artificial diamond powder to afford a porous film, which is then laminated with the drawing type porous film and the laminate is passed through heated uneven rolls made of a metal. Thereby, 15% of whole area of the film is thermally fused to provide the objective film having 0.5-100μm average pore diameter, 1000mmH2O resistance to water pressure and 1000-10000g/m2 day moisture permeability.