An electrode assembly includes a cell stack part having (a) a structure in which one kind of radical unit having a same number of electrodes and separators alternately disposed and integrally combined is repeatedly disposed, or (b) a structure in which at least two kinds of radical units having a same number of electrodes and separators alternately disposed and integrally combined are disposed in a predetermined order, and a fixing part extending from a top surface along a side to a bottom surface thereof for fixing the cell stack part. The one kind of radical unit has a four-layered structure in which first electrode, first separator, second electrode and second separator are sequentially stacked or a repeating structure in which the four-layered structure is repeatedly stacked, and each of the at least two kinds of radical units are stacked by ones to form the four-layered structure or the repeating structure.