NOVELTY - The lithium ion capacitor has anode (1), cathode (2) and an aprotic organic solvent electrolytic solution containing lithium salt as electrolyte. The anode contains a substance capable of reversibly carrying lithium ion and/or anion as an anode active material. The cathode contains a substance capable of reversibly carrying lithium ion as cathode active material. The cathode active material is alkali activated active carbon particles having 50% volume particle diameter of 2-8 mu m. The organic solvent is propylene carbonate.    USE - Lithium ion capacitor is used as power supply for notebook computer, mobile telephone, electric vehicle, hybrid electric vehicle, electrical storage source, electric power-assisted bicycle, electric wheel chair, wind-powered electricity generation and domestic electric appliances.    ADVANTAGE - The lithium ion capacitor has high energy density and improved capacitance.    DETAILED DESCRIPTION - The lithium ion capacitor has an anode, a cathode and an aprotic organic solvent electrolytic solution containing lithium salt as electrolyte. The anode contains a substance capable of reversibly carrying lithium ion and/or anion as an anode active material. The cathode contains a substance capable of reversibly carrying lithium ion as cathode active material. The lithium ion is previously doped with respect to anode and/or cathode such that anode electric potential after short circuiting anode and cathode is 2 V or less (Li/Li+). The cathode active material is alkali activated active carbon particles having 50% volume particle diameter of 2-8 mu m. The organic solvent is propylene carbonate. The active carbon particle is phenol resin group activated charcoal, petroleum pitch group activated charcoal, petroleum coke group activated charcoal or coal coke group activated charcoal.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of structure of the lithium ion capacitor.    Anode (1)    Cathode (2)    Separator (3)    Metal lithium (4)    Conducting wire (5)