PURPOSE: To obtain an electrolytic capacitor which is enhanced in productivity by lessening working processes in number by a method wherein lead wires and the terminals of them located on the outer peripheral surface and the base of a capacitive element except its upside are coated with thermoplastic resin sheathing material, the capacitive element is impregnated with electrolytic solution filled through an opening provided to the sheathing, and then the opening is sealed up.

CONSTITUTION: Terminals 2a and lead wires 2b of lead wires 2 located on the outer peripheral surface 1b and the base 1c of a flat-type capacitive element 1 except its upside 1a are integrally covered with a flat-long-thin thermoplastic resin sheathing 3. The capacitive element 1 is impregnated with electrolytic solution filled through an opening 3a provided to the sheathing 3 on the upside 1a of the capacitive element 1, and then the opening 3a provided to the sheathing 3 is sealed up with thermoplastic resin plug 4. By this setup, an electrolytic capacitor flat, of thin type, and small in space on a circuit board is able to deal with the densification and the miniaturization of an electronic equipment.