An electrode assembly includes a cell stack part having (a) a structure in which one kind of radical unit is repeatedly disposed, or (b) a structure in which at least two kinds of radical units are disposed in a predetermined order, the one kind or the at least two kinds of radical units having same number of electrodes and separators alternately disposed. The one kind of radical unit has four-layered structure in which first electrode, first separator, second electrode and second separator are sequentially stacked or repeating structure of the four-layered structure. Each of the at least two kinds of radical units are stacked by ones to form the four-layered structure or the repeating structure. An outer separator that is a separator among separators of a radical unit positioned at the outermost part of the cell stack part is extended from a side of the cell stack part.