A battery (100) includes an electrode body (80) having a positive electrode and a negative electrode and also includes an exterior case (50) formed in a box-like shape having an inner space corresponding to the electrode body (80). An insulation film (10) is provided between the electrode body (80) and the exterior case (50) to isolate them from each other. The insulation film (10) has a bag-like shape surrounding the electrode body (80) and is placed so as not to come into contact with corners (58) of the inner space.