To provide a film-packaged battery 1 in which battery element 2 formed by collectively joining a plurality of positive and negative extending portions 2a and 2b to positive and negative electrode leads 3a and 3b for each polarity, is surrounded by laminate films 5 and 6 which are formed by laminating at least heat fusion layer 10 and metal layer 11. Protection member 4a having a melting point lower than that of heat fusion layer 10 is arranged at least between each of joining portions 20a and 20b of positive and negative electrode extending portions 2a and 2b, and heat fusion layer 10 of laminate film 5 which layer face the each of joining portions 20a and 20b.