To provide a thin battery prevented from short-circuiting inside the battery even at the occurrence of bulging of the battery while reducing the manufacturing cost and improving the energy density of the battery.

In this battery, a flat spiral electrode body wound of a positive electrode plate 5 and a negative electrode plate 6 through a separator 15 is enclosed inside a laminate case body 3. The positive electrode plate 5 is formed with a positive electrode active material layer 9 on a positive electrode core body 10 of band shape, and the negative electrode plate 6 is formed with a negative electrode active material layer 19 on a negative electrode core body 17 of band shape. A positive electrode current collecting tab 7 is the positive electrode plate 5, and the electrode plate facing the negative electrode current collecting tab 8 is the negative electrode plate 6.