Secondary battery and method for manufacturing secondary battery

This secondary battery is provided with: a flexible exterior member; and a flat battery element housed inside the exterior member, the battery element being provided in such a manner that a positive electrode and a negative electrode are laminated in the thickness direction of the battery element via a separator, the positive electrode and the negative electrode being substantially rectangular sheets, the battery element having a crimped region and a non-crimped region outside the crimped region, the positive electrode, the negative electrode, and the separator are crimped to each other in crimp regions, and the crimp regions are provided at least at positions facing each other in the substantially rectangular peripheral portion. 二次电池具备：外装部件，具有挠性；以及扁平形状的电池元件，收纳于外装部件的内部，电池元件通过隔着隔膜将正极及负极在电池元件的厚度方向上层叠而被设置，正极及负极为大致矩形形状的片材，电池元件具有压接区域和压接区域外的非压接区域，正极、负极以及隔膜在压接区域相互被压接，压接区域至少设置于大致矩形形状的周缘部的相互对置的位置。