Provided is an electrode assembly manufacturing method including a process of cutting a separator included in an electrode assembly to have a margin protruding from an electrode plate. The method includes a first process of manufacturing one type of basic unit sheets having a structure in which electrode materials and separator materials, which are the same in number, are alternately stacked, or two or more types of basic unit sheets having a structure in which electrode materials and separator materials, which are the same in number, are alternately stacked, and a second-A process of cutting a portion of a margin area of the separator materials, which are not covered with the electrode materials, such that the separator materials of the basic unit sheets protrude over a specific distance from edges of the electrode materials.