A new conductive interconnected porous film, useful as a material for a gas diffusion layer which is used in a solid polymer type fuel cell, which satisfies the requirements of a good conductivity, good gas permeability, surface smoothness, corrosion resistance, and low impurities and which is strong in bending and excellent in handling to an extent not obtainable by existing sheet materials of carbon fiber, that is, a conductive interconnected porous film wherein a resin base material part of a thermoplastic resin has a porous interconnected cell structure which is formed by removal of removable particulate matter and has cells of sizes of 10 μm to 50 μm and wherein the resin base material part is comprised of different particle size particles of first carbon particles of large size carbon particles of a diameter of 5 μm or more and second carbon particles of micro size carbon particles of a diameter of 10 nm or more mixed together, and a method of production of the same.