An electrode assembly comprising unit cells (221, 222, 223, 224, 225, 231, 232), each of which is constituted by an electrode plate stack configured to have a structure in which a separator is disposed between electrode plates comprising positive electrodes or negative electrodes, wherein the electrode assembly comprises a combination of two or more kinds of unit cells (221, 222, 223, 224, 225, 231, 232) having different sizes, the unit cells (221, 222, 223, 224, 225, 231, 232) are stacked in a height direction on a basis of a plane, two or more of the unit cells (221, 222, 223, 224, 225) located at a lower part of the electrode assembly, i.e. two or more base unit cells (221, 222, 223, 224, 225), are wound using a single sheet-type separation film to constitute an integrated base structure, and the others of the unit cells (231, 232) excluding the base unit cells (221, 222, 223, 224, 225), i.e. sub unit cells (231, 232), are stacked in a state in which a separator is disposed between the respective sub unit cells (231, 232), characterized in that the base unit cells (221, 222, 223, 224, 225) are bi-cells, each of which is configured to have a structure in which one or more positive electrodes and one or more negative electrodes are stacked in a state in which a separator is disposed respectively between the positive electrodes and negative electrodes and in which the electrodes are located at opposite major surfaces of the base unit cell have the same polarity, in which the bi-cells have the same size, each of the sub unit cells (231, 232) is a full-cell, which is configured to have a structure in which the electrode plates located at opposite major surface of the sub unit cell (231, 232) have different polarities, in which the sub unit cells (231, 232) preferably have the same thickness, and one of the base unit cells (221, 222, 223, 224, 225) and a corresponding one of the full-cells (231, 232) adjacent to the base unit cell are configured such that the electrode plate of the base unit cell is a negative electrode and the electrode plate of the full-cell is a positive electrode. the electrode assembly comprises a combination of two or more kinds of unit cells (221, 222, 223, 224, 225, 231, 232) having different sizes, the unit cells (221, 222, 223, 224, 225, 231, 232) are stacked in a height direction on a basis of a plane, two or more of the unit cells (221, 222, 223, 224, 225) located at a lower part of the electrode assembly, i.e. two or more base unit cells (221, 222, 223, 224, 225), are wound using a single sheet-type separation film to constitute an integrated base structure, and the others of the unit cells (231, 232) excluding the base unit cells (221, 222, 223, 224, 225), i.e. sub unit cells (231, 232), are stacked in a state in which a separator is disposed between the respective sub unit cells (231, 232), characterized in that the base unit cells (221, 222, 223, 224, 225) are bi-cells, each of which is configured to have a structure in which one or more positive electrodes and one or more negative electrodes are stacked in a state in which a separator is disposed respectively between the positive electrodes and negative electrodes and in which the electrodes are located at opposite major surfaces of the base unit cell have the same polarity, in which the bi-cells have the same size, each of the sub unit cells (231, 232) is a full-cell, which is configured to have a structure in which the electrode plates located at opposite major surface of the sub unit cell (231, 232) have different polarities, in which the sub unit cells (231, 232) preferably have the same thickness, and one of the base unit cells (221, 222, 223, 224, 225) and a corresponding one of the full-cells (231, 232) adjacent to the base unit cell are configured such that the electrode plate of the base unit cell is a negative electrode and the electrode plate of the full-cell is a positive electrode.