The invention aims to allow carbon dioxide, which is generated upon decomposition of lithium carbonate contained in a positive electrode mixture layer, to easily flow toward the outside of a flat wound electrode body, and further aims to rapidly raise the pressure inside a battery and to reliably operate a pressure-sensitive current interrupt mechanism before the temperature inside the battery rises to such an extent as causing an abnormal state, e.g., smoking, firing, or a burst.A nonaqueous electrolyte secondary battery (10) according to one embodiment of the present invention includes a pressure-sensitive current interrupt mechanism. An insulating tape (11b) is bonded onto a positive electrode mixture layer (11a) in at least one of a winding start-side edge portion and a winding end-side edge portion of a positive electrode plate (11) in a flat wound electrode body (14) at a position opposing to a separator (13), the insulating tape extending in a widthwise direction of the positive electrode mixture layer (11a).