A secondary battery , comprising: a positive electrode ; a negative electrode ; a battery case housing the positive electrode and the negative electrode ; a positive electrode lead electrically connected to the positive electrode ; and an electrical insulating tape covering a part of the positive electrode lead , wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector , the positive electrode current collector has, at a longitudinally central part of the positive electrode active material layer on the positive electrode current collector , an exposed part on which no positive electrode active material layer is formed, the positive electrode lead has a first end part connected to the exposed part and an extension part extending from the first end part toward an outside of a peripheral part of the positive electrode current collector , an electrical insulating layer is disposed on an outer surface of the first end part of the positive electrode lead , the electrical insulating layer is covered with the electrical insulating tape , and the electrical insulating tape covers a boundary part between the exposed part and the positive electrode active material layer , characterized in that the insulating tape has a larger width than that of the electrically insulating layer as measured in the longitudinal direction of the positive electrode , and in that the insulating tape includes a substrate layer containing an organic material and an adhesive layer adhering to the electrical insulating layer and the exposed part . a positive electrode ; a negative electrode ; a battery case housing the positive electrode and the negative electrode ; a positive electrode lead electrically connected to the positive electrode ; and an electrical insulating tape covering a part of the positive electrode lead , wherein the positive electrode has a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector , the positive electrode current collector has, at a longitudinally central part of the positive electrode active material layer on the positive electrode current collector , an exposed part on which no positive electrode active material layer is formed, the positive electrode lead has a first end part connected to the exposed part and an extension part extending from the first end part toward an outside of a peripheral part of the positive electrode current collector , an electrical insulating layer is disposed on an outer surface of the first end part of the positive electrode lead , the electrical insulating layer is covered with the electrical insulating tape , and the electrical insulating tape covers a boundary part between the exposed part and the positive electrode active material layer , characterized in that the insulating tape has a larger width than that of the electrically insulating layer as measured in the longitudinal direction of the positive electrode , and in that the insulating tape includes a substrate layer containing an organic material and an adhesive layer adhering to the electrical insulating layer and the exposed part . <EOS>