An electrode portion of a lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolytic layer between the positive electrode and the negative electrode, wherein the positive electrode and the negative electrode comprise a current collector and an active material layer laminated on the surface of the current collector, wherein current collector end portions of the positive electrode and the negative electrode; and sections of another negative electrode and positive electrode laminated respectively on the positive electrode and the negative electrode, which are facing the current collector end portions, are coated by an insulation coating.
