There is provided an electrode assembly including a first electrode laminate having at least one or more electrode units having a first area, stacked therein, a second electrode laminate having at least one or more electrode units having a second area smaller than the first area, stacked therein, and a step portion provided by stacking the first electrode laminate and the second electrode laminate in a direction perpendicular to a plane and having a step formed due to a difference in areas of the first and second electrode laminates, the electrode assembly being characterized in that, the electrode unit is wound by a rectangular-shaped separation film such that at least a portion of the rectangular-shaped separation film covers the step portion of the electrode assembly, and a step having a shape identical to the step portion is formed.
