A porous polyimide having a finely cellular structure and having a low dielectric constant and heat resistance. The porous polyimide can be produced by a process comprising adding a dispersible compound to a polyimide precursor to form a micro-domain structure in which the dispersible compound is dispersed in the polymer so as to have a size smaller than 10 nullm and then removing the dispersible compound by extraction with supercritical carbon dioxide to thereby make the precursor porous, wherein the interaction parameter nullAB between the polyimide precursor A and the dispersible compound B is larger than 3. This porous polyimide has an average cell diameter smaller than 5 nullm and a dielectric constant of 3 or lower.