A gasket (4) or collecting electrodes (1) are used as members for separating the inside from the outside of an electrical double-layer capacitor and small holes (5) are provided therein through which the internal air is drawn. Thus the internal pressure becomes lower than the atmospheric pressure and the pressure difference is generated between the inside and the outside.Due to this pressure difference, collecting electrodes (1) are pressed to solid polarizing electrodes (2). Hence the resistance in the contacts between the collecting electrodes and the solid polarizing electrodes can be reduced. Since the contact force is obtained by the pressure difference between the inside and the outside, the contact force is applied equally to every part of the contacts. As a result, there is no contact where its contact resistance is not reduced.Further, there is no need of provision of any device for generating the contact force outside the electrical double-layer capacitor.