A lithium ion secondary battery comprises a case; a positive electrode foil having a current collector foil on which a positive electrode material is coated; an negative electrode film having a current collector film on which an negative electrode material is coated; a separator sandwiched between the positive electrode film and the negative electrode film, the films and the separator being arranged in multiple layers to form a group of electrodes enclosed in the case, a positive collector disc plate connected to the positive electrode side of the group of the electrodes, and an negative collector disc plate connected to the negative electrode side of the group of the electrodes. Each of the current collector foils has a non-coated portion extended along one side of the foils, a part or the entire of the non-coated portion being exposed from a side of the separator. At least one of the collector disc plate is welded to the side of the exposed non-coated portion of the group of the electrodes. The periphery of the collector disc plate has an annular portion, which is bent towards the group of electrodes.