A packaged battery, an assembled battery, and a film-covered battery, which can prevent a dangerous state involving a high-pressure gas filled in the film-covered battery while ensuring a sealing reliability, are provided. The Packaged battery includes film-covered battery 1 including a battery element and exterior films forming a sealed space housing the battery element, and holding member 10 holding film-covered battery 1. The sealed space includes a housing section housing the battery element, and a pocket communicating with the housing section to expand when the pressure in the sealed space increases. The pocket includes a safety valve which activates when the pocket expands. Holding member 10 includes an opening and a cavity fitting the housing section therein. When the housing section is fitted into the cavity, at least part of the pocket and the safety valve protrude to the outside of the holding member from the opening.