A capacitor for use in a hybrid vehicle and the like has a structure contrived to achieve reduction in size, increase in capacitance and decrease in resistance. An element has a pair of positive and negative electrodes, each comprising a collector made of a metallic foil having a carbon-containing electrode layer formed thereon, the electrodes rolled up with a separator interposed therebetween to form a pair of electrode terminations at opposite sides of the element. A dimension of one of the electrode terminations is set shorter than that of the other electrode termination. This structure achieves an increase in capacitance and decrease in resistance since it can increase an effective area of electrode surfaces under a restricted condition of keeping the same height of the element as it is placed inside a casing of given dimensions.