Disclosed is a conductive polymer, which is doped with an acid and has a weight-average molecular weight of 5,000 or less when provided in the form of a base type, with a solubility of 3% or more in a polar organic solvent. Because the conductive polymer is soluble in various polar organic solvents, the solvent may be freely selected depending on the end use of the conductive polymer and thus the conductive polymer has a very wide range of industrial applications. A method of preparing the conductive polymer is also provided, which is simple and generates a small amount of wastewater and thus reduces the preparation cost and is environmentally friendly.