To prevent the lowering of connection strength between an electrode lead and a rivet by forming a washer which does not come into contact with the rear face of a sealing body of aluminum alloy in two washers fastened to the rear face of the sealing body by means of the rivet across the electrode lead of a capacitor element.

The number of outer connection terminals 18, which corresponds to the electrode foil of a capacitor element 12, are formed on the surface of the sealing body 16 of an electrolytic capacitor 10 and they are fixed on the surface of the sealing body 16 by the rivet 20 made of aluminum. Two washers 22 and 24 are installed in the rivet 20 of a part protruded from the rear face of the sealing body 16 across the electrode lead 123 of the capacitor element 12. The washers 22 and 24 fasten the rear face of the sealing body 16 by the rivet 20 and the washer 22 which comes into contact with the rear face of the sealing body 16 is formed of aluminum. On the other hand, the washer 24 which does not come into contact with the rear face of the sealing body 16 is formed of aluminum alloy containing magnesium.