An electrically conductive polymer composition contains an electrically conductive polymer obtained by using a polymer in the form of cations composed of repeating structural units of 3,4-ethylene dioxythiophene and polystyrene sulfonic acid as anions and further contains naphthalene sulfonic acid as an additive. A solid electrolytic capacitor 101 or a surface-mount transmission line element 102 has a polypyrrole conductive polymer layer 3 as a first solid electrolyte and a poly(3,4-ethylene dioxythiophene) conductive polymer layer 4 as a second solid electrolyte.