TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - The conductive polymer is formed on the carbon nanotubes by electrolytic polymerization carried out using a working electrode immersed in a solution containing the monomer of the conductive polymer. The working electrode is a carbon nanotube containing electrode comprising a collector with electron conductivity, and an electrode active material-containing layer formed on the collector. The electrode active material-containing layer comprises carbon nanotubes and exhibits electron conductivity. The electrolytic polymerization is carried out using a solution containing a monomer as the structural material of the conductive polymer, and the carbon nanotubes. The separator is formed of an insulating porous body, and at least a portion of the electrolyte solution is contained inside the two electrodes and the separator. The first electrode, the second electrode and the separator each have sheet-like shapes. The case is formed using at least a pair of mutually opposing composite package films, and the composite package films comprise at least an innermost layer made of a synthetic resin in contact with the electrolyte solution, and a metal layer situated over the innermost layer.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The electrode active material-containing layer further contains activated carbon.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The electrode active material-containing layer further contains activated carbon.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The conductive polymer has at least a molecular structure having a repeating unit based on a monomer, thiophene (substituted at 3 and 4 positions by R1 and R2) (preferably 3-methylthiophene, 3-butylthiophene, 3-phenylthiophene, 3-methoxythiophene and ethylenedioxythiophene) or pyrrole (substituted at 1, 3 and 4 positions by R3, R4 and R5 respectively) (preferably aniline, indole, pyridine and diaminoanthraquinone).R1, R2, R4 and R5=H, alkyl, aryl or alkoxy;R1R2 and R4R5=divalent group;R3=H or alkyl. EXAMPLE - Multi wall carbon nanotubes (12 nm diameter, 100 microns length) (40 parts by weight (pbw)) and fluororubber binder (60 pbw) were mixed and methyl isobutyl ketone was added as solvent to obtain a slurry-like containing layer. The obtained coating solution was coated onto an aluminum foil (20 microns) as collector and was dried at 150degreesC. The drying was followed by rolling to obtain a carbon-nanotube containing electrode. The electrode was placed in an electrolytic bath containing an electrolyte solution having monomer solution obtained by dissolving thiophene (0.3 mol dm-3) in a solution of LiBHF4 (1 Mol dm-3) in propylene carbonate. Electrolytic polymerization was carried out at 4.4 V for 20 minutes while maintaining a constant potential to obtain an electrode having an area of 1.77 cm2.