If an organic solvent is used for dissolving pyrrole, then organic conducting salts such as alkali and ammonium salts of n-dodecylsulphate, aromatic sulfonic acids, phthalocyanine sulfonic acids, polystyrene sulfonic acids, campher sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid, long chain fatty acids or benzene sulfonic acid are preferably used therewith.