An electric double layer capacitor having an electrolyte solution impregnated to an element including a positive electrode and a negative electrode facing each other with a separator interposed therebetween, wherein an electrode containing a carbon material having a specific surface area of at least 500 m.sup.2 /g is used as the positive electrode and/or the negative electrode, and the separator is made of a glass fiber sheet containing from 2 to 60 wt % of glass fibers having fiber diameters of at most 1 .mu.m.