To provide a method for producing an aqueous dispersion which contains a conductive polymer component and can form conductive thin films having excellent transparency and conductivity, and to provide an aqueous dispersion obtained by the method.

This method for producing an aqueous dispersion of the complex of a poly(3,4-dialkoxythiophene) with a polyanion is characterized by including a process for polymerizing a 3,4-dialkoxythiophene with an oxidizing agent in the presence of a polyanion in an aqueous solvent, wherein the polyanion is polystyrene sulfonic acid having a specific mol. wt. and a sulfonation rate or another polystyrene sulfonic acid having a specific sulfonation rate, or the pH of the reaction solution in the time of the reaction is controlled to a specific value.