Provided is a secondary battery suitable for a portable information terminal or a wearable device, or an electronic device having a novel structure with a variety of forms and a secondary battery that fits the form of the electronic device. The secondary battery is sealed using a film having projections that can reduce stress on the film caused when external force is applied. The film has a pattern of projections formed by pressing (e.g., embossing). A top portion of each of the projections has a region thicker than a bottom portion of each of the projections. The thickness of the top portion of each of the projections is 1.5 or more times, preferably 2 or more times, as large as that of the bottom portion of each of the projections, and is a thickness such that each of the projections has a convex space.