An electric double layer capacitor has a pair of activated carbon electrodes and an organic solution in which an electrolyte is dissolved in an organic solvent. An electrolyte solution is also provided. In the electric double layer capacitor, at least one of cycloalkane, cycloalkene, or derivatives thereof is contained in at least one of the activated carbon and the organic electrolyte solution. The organic solvent contains a main solvent and an additive solvent. The main solvent contains propylenecarbonate in a range of from 99.9 to 70 wt %, and at least one of ethylenecarbonate and dimethylcarbonate in a range of from 0.1 to 30 wt %, and the additive solvent contains cycloalkane in a range of from 5 to 30 wt % to the total amount of the organic solvent.