A method includes the following steps: forming a porous anode body using powder of valve metal or an alloy thereof; forming a dielectric layer on the surface of the anode body; soaking the anode body having the dielectric layer in a liquid containing a conductive-polymer monomer, thereby making the monomer adhere to the dielectric layer of the anode body; forming a first conductive polymer layer by soaking the anode body having the monomer adhered thereto in an oxidizing agent solution, thereby polymerizing the monomer by liquid-phase chemical polymerization; forming a second conductive polymer layer by bringing the conductive-polymer monomer into contact with the surface of the anode body having the first conductive polymer layer in a gas phase, thereby polymerizing the monomer by gas-phase chemical polymerization; and forming a third conductive polymer layer by soaking the anode body having the second conductive polymer layer in a liquid containing a monomer of a conductive polymer layer, thereby polymerizing the monomer by electrolytic polymerization.