The present invention provides a highly conductive separator of which surface is coated with conductive polymer molecules, and provides an electrolytic capacitor having a low ESR characteristic using the separator. The conductive separator is formed by sticking the conductive polymer molecules to an insulating separator substrate by chemical oxidative polymerization, and the stuck amount of the conductive polymer molecules per basis weight of the separator substrate is set in the range of 3 to 30 g/m.sup.2. Conductive polymer molecules that are hardly de-doped can be formed in the electrolyte for driving by chemical oxidative polymerization, so that an electrolytic capacitor having high capacitance and low ESR can be obtained.