NOVELTY - An electric storage device (10) comprises a positive electrode system including positive electrode(s) (13, 14) having a current collector and positive-electrode mixture layer; and negative electrode system including a negative electrode (15) including a current collector (16) and negative-electrode mixture layer. The positive electrode system includes two positive-electrode mixture layers (20, 22) connected to each other, and having a different thickness. A through-hole (16a) is formed on the current collector arranged between the positive-electrode mixture layers.    USE - As an electric storage device that is mounted to e.g. electrical vehicle, and hybrid vehicle; and as an hybrid capacitor.    ADVANTAGE - Since positive electrodes having different charging/discharging characteristics are provided, an energy density and an output density is enhanced. Ions can move between the positive-electrode mixture layers via the through-holes of the negative-electrode current collector, where a variation in the potential of the positive electrodes is canceled. Thus, the durability of the electric storage device is ensured.    DETAILED DESCRIPTION - An electric storage device (10) comprises a positive electrode system including positive electrode(s) (13, 14) having a current collector and positive-electrode mixture layer; and negative electrode system including a negative electrode (15) including a current collector (16) and negative-electrode mixture layer. The positive electrode system includes two positive-electrode mixture layers (20, 22) connected to each other, and having a different thickness. A through-hole (16a) is formed on the current collector arranged between the positive-electrode mixture layers. The two positive-electrode mixture layers are electrically connected, and ions move between the mixture layers via the through-hole. Both of the positive-electrode mixture layers contain an active carbon. The positive electrode system includes a first positive electrode and a second positive electrode that sandwich the negative electrode, and the through-hole is formed on the current collector of the negative electrode arranged between the first positive-electrode mixture layer of the first positive electrode and the second positive-electrode mixture layer of the second positive electrode. The electric storage device also comprises a lithium ion source that is in contact with at least one of the negative and positive electrode, where lithium ions are doped from the lithium ion source into at least one of the negative and positive electrode; device structure of a laminated type in which the electrodes are alternately laminated, or a device structure of a wound type in which the electrodes are laminated and wound.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view of an internal structure of an electric storage device.    Electric storage device (10)    Positive electrodes (13, 14)    Negative electrode (15)    Current collector of negative electrode (16)    Through-hole (16a)    First positive-electrode mixture layer (20)    Second positive-electrode mixture layer (22)