A process for producing a dispersion containing an electroconductive polymer is provided with which a low-viscosity dispersion containing a conjugated electroconductive polymer that has excellent electroconductivity can be obtained and an improvement in production efficiency is rendered possible. The process for producing a dispersion containing an electroconductive polymer comprises a polymerization step in which a monomer serving as constituent units of the conjugated electroconductive polymer is polymerized in a liquid mixture comprising the monomer, a polyanion, and a dispersion medium, thereby producing a polymer and a dispersion step in which the liquid reaction mixture obtained in the polymerization step is subjected to a dispersion treatment to produce a dispersion of the polymer. A dispersion medium is added at least once anytime during the period from completion of the polymerization step to before completion of the dispersion step so that the mass concentration (B) of the polymer in the dispersion after the dispersion step is lower than the mass concentration (A) of the polymer in the liquid reaction mixture.