the invention concerns an ultra thin polymer film electret comprising a polymer and a substrate having a surface electric charge , wherein a side chain of the polymer and the substrate are physically or chemically bonded . a method of manufacturing an ultra thin polymer film electret comprising : adsorbing a monomolecular film comprising a unsaturated group or a laminated film comprising the monomolecular film on to a substrate surface , irradiating the monomolecular film or the laminated film with an energy beam to polymerize the unsaturated groups and applying a high voltage to the film is also disclosed . further , a method of manufacturing an ultra thin polymer film electret comprising : physically bonding a side chain of the polymer to a substrate surface to form a thin film and applying a high voltage to the thin film is also disclosed .