There is provided a conductive polymer having high conductivity with excellent heat resistance. Using the conductive polymer, there can be provided solid electrolytic capacitors having low ESR, high reliability, and less leakage current. There can be also provided conductive films having high conductivity and superior heat resistance. There is provided a conductive polymer dispersion liquid obtained by a method in which in the presence of a copolymer from styrenesulfonic acid, and at least one kind of a non-sulfonic acid monomer selected from the group consisting of methacrylate, acrylate, and an unsaturated hydrocarbon containing alkoxysilane compound or its hydrolysate, thiophene or its derivative is polymerized by oxidation polymerization in water, or in an aqueous solution comprising a mixture of water and a water miscible solvent to produce the conductive polymer dispersion liquid. Using the conductive polymer as solid electrolyte, a solid electrolyte capacitor can be provided. Also, using the conductive polymer, a conductive film can be provided.