Secondary Battery

A positive electrode sheet is electrically connected to a positive terminal with a positive electrode current collector, a deformable plate, and a conductive member interposed therebetween. When the pressure inside a battery is higher than or equal to a predetermined value, the deformable plate is deformed toward a sealing plate and an annular groove formed on a base portion of the positive electrode current collector is broken due to deformation of the deformable plate so that a conductive path between the positive electrode sheet and the positive terminal is disconnected. A first insulating member disposed between the deformable plate and the base portion of the positive electrode current collector includes a first rotation preventing protrusion on a surface thereof on a wound electrode body side and outside an outer circumferential edge of the base portion of the positive electrode current collector.