Process for producing dispersion containing electroconductive polymer

A method for producing a conductive polymer-containing dispersion, the method comprising:

• a polymerization step of subjecting a monomer that is to be a constitutional unit of a conjugated conductive polymer to a polymerization reaction in a mixed solution comprising the monomer, a polyanion, and a dispersion medium to produce a polymerized product;
• and
• a dispersion treatment step of performing a dispersion treatment on a reaction solution obtained in the polymerization step to prepare a dispersion of the polymerized product, wherein
• the dispersion medium is added one or more times during the dispersion treatment step to make a mass concentration (B) of the polymerized product in the dispersion after the dispersion treatment step lower than a mass concentration (A) of the polymerized product in the reaction solution,
• the dispersion medium is added after a time course of at least 10% of a time required for the dispersion treatment from a beginning of the dispersion treatment, and
• the mass concentration (B) is not more than 0.95 times a mass concentration (C) of the polymerized product in the dispersion before the beginning of the dispersion treatment.