A cell is provided. The cell includes a cell element including a positive electrode, a negative electrode, an electrolyte and a laminate film including an exterior layer, a metal layer, an interior layer, and a welded layer formed of the interior layer; wherein a thickness of the welded layer is larger than 5 μm in a flat portion of the interior layer, wherein the welded layer increases in thickness from the flat portion to an end portion of the welded layer, and wherein when a thickness of the laminate film is t, a thickness of the interior layer is p and a thickness of the laminate film in the welded layer is t1, a following equation is satisfied: t×2−p×2+5