The present invention provides a process for producing an activated carbon having a small average particle diameter, a uniform particle size and a relatively large specific surface area suitable for an electric double layer capacitor electrode, in an easy and cost effective manner. The process comprises calcining an easily graphitizable carbon material such as petroleum coke or coal coke, used as the raw material under an oxidizing gas atmosphere, adjusting the particle size of the carbon material, and then activating the carbon material. The use of the activated carbon produced by the process of the present invention in an electrode can provide an electric double layer capacitor having a large capacitance per unit volume.