LITHIUM ION CAPACITOR

In a lithium ion capacitor provided with a positive electrode, a negative electrode, and a non-protonic organic solvent electrolytic solution of a lithium salt as an electrolytic solution, a positive electrode active material is a material that can reversibly dope lithium ion and/or anion. A negative electrode active material is a material that can reversibly dope lithium ion. The lithium ion is doped in advance to a negative electrode and/or a positive electrode so that a positive electrode potential after the positive electrode and the negative electrode are short-circuited may be 2.0 V or less. When the capacitance per unit weight of positive electrode, weight of the positive electrode active material, electrostatic capacitance per unit weight of negative electrode and weight of the negative electrode active material, respectively, are expressed by C + (F/g) , W + (g) , C - (F/g) and W - (g), a value of (C - × W - ) / (C + × W + ) is 5 or more.