An electric double layer capacitor has a pair of current collectors, a positive polarizable electrode which is provided on one of the pair of current collectors, includes activated carbon of a weight W.sub.+ and has a capacitance C.sub.+, a negative polarizable electrode which is provided on the other of the pair of current collectors, includes activated carbon of a weight W.sub.- and has a capacitance C.sub.-, a separator interposed between the positive and negative polarizable electrodes, and an organic electrolytic solution which impregnates at least the positive and negative polarizable electrodes and the separator, wherein C.sub.-/C.sub.+=0.6 to 1.0 and W.sub.-/W.sub.+=1.1 to 2.0. Even when continuously charged at a high applied voltage, the electric double layer capacitor has a high retention of capacitance and a low rise in internal resistance, and thus has an excellent durability.