<p>A conventional electrolyte composition composed of a conductive polymer and an ionic liquid has a problem in durability (especially in impedance characteristics) when used in a conductive polymer capacitor. Disclosed is an electrolyte composition having excellent durability, which uses an ionic liquid containing a carboxylic acid as an anionic component. The carboxylic acid is preferably one having a hydroxy group or an amino acid. The electrolyte composition is preferably composed of a conductive high-molecular-weight monomer (A) and an ionic liquid (B). In addition, the electrolyte composition preferably contains an ammonium salt, an amine salt, a quaternary ammonium salt or the like.</p>
