Abstract: A battery pack has a flat battery cell, which includes a flat electric power generating element, at least one armor material for sealing the electric power generating element, and positive and negative tabs (1a, 2a) extending from the electric power generating element to the outside of the armor material through a sealing of the armor material; a circuit board (6) connected to the positive and negative tabs; and a container (16) having two main walls extending along two main surfaces of the flat battery cell. At least a portion of the circuit board is positioned in a space (8) defined by a sealing of the armor material beside the circuit board and the inner surface of the container. At least one of the two main walls of the container is at least partially formed of a metal plate (12a, 14a).