A battery module having first and second cylindrical battery cells, each of the first and second cylindrical battery cells having a negative electrode terminal and a positive electrode terminal, a metal plate configured to connect, in series, the first cylindrical battery cell and the second cylindrical battery cell, a shrinkable tube in which the first and second cylindrical battery cells are mounted, first and second PTC elements respectively provided to the first and second cylindrical battery cells, first insulating members provided between the first and second PTC elements and the shrinkable tube, second insulating members respectively provided between the first and second PTC elements and the first and second cylindrical battery cells, insulating sheets respectively configured to seal an upper surface and a lower surface of the shrinkable tube, and a connection part protruding outward from the shrinkable tube and configured to connect the first and second cylindrical battery cells to an external electronic apparatus in provided.