A solid-state electrolytic capacitor including a stacked body of a solid-state electrolytic capacitor element unit and an electrode conversion board. The unit includes two kinds of solid-state electrolytic capacitor elements. Each of first kind of solid-state electrolytic capacitor elements uses an anode body having a total thickness of an aluminum foil of 350 μm and a residual core thickness, i.e., the total thickness minus the thickness of an etched layer, is 50 μm. A second kind of solid-state electrolytic capacitor element provided on the mounting surface side uses an anode body having a total thickness of an aluminum foil of 150 μm and a residual core thickness is 50 μm. The electrode conversion board includes external anode and external cathode terminals that are arranged In a checkered manner and also includes, on the side opposite to the board, anode electrode and cathode electrode plates.