Abstract: A stacked electric double layer capacitor including a peripheral portion of an intermediate electrode plate held between peripheral portions of first and second case halves to be welded to each other, thereby defining first and second closed spaces for storing first and second capacitor elements, respectively. The first and second electrode plates are exposed by openings provided in the first and second case halves to form external terminal means, respectively. The two capacitor elements, stacked in series with each other are stored in the case, formed by joining the case halves to form a stacked electric double layer capacitor which can be reduced in thickness with substantially no leakage of electrolyte.