The utility model provides a battery pack. By dissipating heat generated by single batteries, the safety is improved, the service life is prolonged, and the production can be carried out efficiently. The battery pack (1) comprises a core packet (20), a shell (10) and a heat transfer resin part (30). A shell component (12) of the shell (10) is bowl-shaped, and single batteries (21 to 25) of the core packet (20) are configured to enable cylinder shafts to be along the internal surface of the bottom wall of the shell component (12). The heat transfer resin part (30) is formed by filling in the whole range from the internal surface of the bottom wall to the opening edge of the side wall of the shell component (12), so that part of each of the two cylinder ends of each of the single batteries (21 to 25) tightly contacts part of the cylinder peripheral surface, the rest part of each of the single batteries (21 to 25) does not contact the heat transfer resin part (30), and at least one part of each single battery is toward a space (10a) of the shell (10). Part of each of conductor plates (27 and 28) which are connected with the single batteries (21 to 25) also contacts the heat transfer resin part (30).