An electrical double layer capacitor comprises an element and a case which houses the element. The element has an anode charge collector, anode, separator, cathode and cathode charge collector. The anode and cathode consist of a porous layer containing electrically conducting porous particles as a constituent material. The anode charge collector is disposed in electrical contact with the anode. The cathode charge collector is disposed in electrical contact with the cathode. The thickness of the element is 600 .mu.m or less. The sum of the anode thickness and cathode thickness is set to 80% or less of the thickness of the element.