An electric double-layer capacitor includes a carbon composite electrode
which serves as a polarizing electrode and made of a single-layer carbon
nanohorn aggregate having a specific structure and a very large surface
area. The single carbon nanohorn aggregate is mixed with a phenol resin,
the mixture is formed and heated to produce a carbon composite electrode.
The carbon composite electrode is impregnated with an electrolyte to
become a polarizing electrode. An electric double-layer capacitor
includes this polarizing electrode has a large capacitance and is capable
of discharging with large current.