A secondary battery suitable for a portable information terminal or a wearable device is provided. An electronic device having a novel structure that can have various exterior forms and a secondary battery that fits the forms of the electronic device are provided. The problem that strong external force unintentionally bends a secondary battery or an electronic device with a built-in secondary battery beyond the limits, resulting in a too small radius of curvature can be solved. The secondary battery has a structure in which a positive electrode and a negative electrode are included with a separator interposed therebetween. Between this structure and an exterior body, a thermoplastic substance which becomes flexible in the range around a surface temperature of human skin, higher than or equal to 30° C. and lower than or equal to 37° C., is provided.