A solid electrolytic capacitor excellent in adhesion to a solid electrolyte with excellent ESR and heat resistance can be provided without reducing the material characteristics of a separator. This solid electrolytic capacitor comprises a capacitor element formed by winding an anodic foil prepared from a chemical conversion foil obtained by anodizing a metal having a valve action and a counter cathodic foil through a separator and a solid electrolyte employed as an electrolyte, while the separator is prepared from aramid fiber, and a silane coupling agent adheres to voids of the aramid fiber.