A closed type capacitor (1) includes: an external container (10) which cuts off gas; a pair of polarized electrodes contained in the external container (10); a separator arranged between the electrodes; and a non-aqueous electrolytic liquid containing electrolyte and a non-aqueous organic solvent if necessary. The external container (10) has an opening (10A) for communication between inside and outside the container and a valve mechanism (13) which is arranged to cover the opening (10A) and which is opened and closed by the pressure difference between the inside and outside the container (10). The electrolyte contains more than 30 mass % of ion liquid. This closed type capacitor can minimize separation of electrolyte in the valve path.