Battery and process for examining battery

The present invention relates to lightweight of a battery and a battery having shielding effect and high reliability without sealing leakage. In case of a conventional battery having a laminated sheet material as a battery case for storing a battery body, the metal foil on the laminated sheet does not contact to either a positive electrode or a negative electrode and electric potential is unstable. Therefore, there was a problem that it was impossible to obtain electrical shielding effect. In order to maintain the function of the sealed part in the battery case, an extended part extended from the sealed part is disposed at a position where it overlaps with the positive electrode lead or the negative electrode lead, and by jointing the lead and the extended part with the conductive material piercing therethrough, the metal foil on the laminated sheet material of the battery case is electrically connected to the lead to maintain the electric potential of the battery case to the electric potential of the positive electrode or the negative electrode.