A storage device (1) for bulk material intended for powdery materials, includes a flexible container (2) for bulk material and an insulating inner liner (3), of which the surface resistivity is greater than 1.0×1012 &OHgr;, without a static electricity conductive layer and without a static electricity dissipation layer, the inner lining (3) covering the inner walls of the container, the inner lining (3) including micro-perforations that pass there through, distributed over the whole surface of the inner lining (3) in such a way that the breakdown voltage of the inner liner (3) is lower than 4 kV and the breakdown voltage of the wall of the container is lower than 6 kV.