Disclosed herein is a double winding type electrode assembly constructed in a structure in which a cathode and an anode are opposite to each other while a separator is disposed between the cathode and the anode, wherein the electrode assembly is manufactured by preparing a plurality of cell units, each cell unit having a cathode sheet and an anode sheet, of a predetermined size, wound, while a separator is disposed between the cathode sheet and the anode sheet, each cell unit being elliptical in section, and sequentially winding the cell units while arranging the cell units on a long separator sheet.