Battery pack

A battery pack includes: a plurality of flat-shaped cells each including a generator element sealed by a laminate film; a case for accommodating the cells so as to be laminated in a thickness direction thereof, the case having an opening formed at least at one end thereof; a lid member fixed to the opening of the case and pressing the laminated cells in a laminating direction thereof; a bottom member provided between the case and the cell located at an end of the laminated cells on a side opposite to the opening of the case; a first tray provided between the cells and brought into contact with the case; a second tray provided between the lid member and the cells and brought into contact with the case; and a third tray provided between the bottom member and the cells and brought into contact with the case. The lid member and the bottom member are formed of a material having a thermal conductivity lower than a thermal conductivity of any one of the first tray, the second tray and the third tray.