A solid electrolytic capacitor includes a positive electrode foil made of metal, a dielectric oxide layer provided on a surface of the positive electrode foil, a separator provided on the dielectric oxide layer, a solid electrolyte layer made of conductive polymer impregnated in the separator, a negative electrode foil facing the dielectric oxide layer across the solid electrolyte layer, and a phosphate provided on the dielectric oxide layer. This solid electrolytic capacitor reduces a leakage current.