An electric double-layer capacitor comprising an electrode containing an activated carbon, an electrolytic solution containing an electrolyte and a separator, wherein the electrolyte is an imidazolium salt represented by the following formula (1) (wherein R and R′ each independently represent alkyl group having 1 to 6 carbon atoms, R1 to R3 each independently represent hydrogen atom or alkyl group having 1 to 6 carbon atoms and X− represents a counter ion), and the activated carbon is produced by carbonizing an organic aerogel obtained by polymerizing a phenolic compound having at least one hydroxyl group in its molecule with an aldehyde compound in an aqueous solvent in the presence of a basic catalyst.