A secondary battery comprising: an outer can having an opening, a sealing body sealing the opening of the outer can, the sealing body including a lid plate arranged at the opening and a terminal of one electrode attached to the lid plate; an electrode group formed by stacking the one electrode and the other electrode via a separator, the electrode group being housed with an electrolyte inside the outer can; a current collector joined to the one electrode of the electrode group; and a current collecting lead interposed between the sealing body and the current collector and joined to the sealing body and the current collector to electrically connect the current collector and the sealing body, characterized in that the current collecting lead has a top wall located on a side of the sealing body, a bottom wall facing the top wall and located on a side of the current collector, and a pair of side walls extending between a side edge of the top wall and a side edge of the bottom wall, and facing each other, and the top wall is divided by a top wall slit extending along a long side direction and includes one divided first half body part and one divided second half body part including faced parts (52c and 54c) facing the bottom wall, and extension parts (52a, 52b, 54a and 54b) extending outward from the faced parts (52c and 54c), the extension parts (52a, 52b, 54a and 54b) being joined to the lid plate, wherein the extension parts (52a, 52b, 54a and 54b) have a welded part including a portion in which a lead protrusion formed out of the top wall by punch press processing protruding to the side of the sealing body is deformed by heat and wherein the current collector has a welded part including a portion in which a current collector protrusion formed out of the current collector by punch press processing protruding to a side of the current collecting lead is deformed by heat. an outer can having an opening, a sealing body sealing the opening of the outer can, the sealing body including a lid plate arranged at the opening and a terminal of one electrode attached to the lid plate; an electrode group formed by stacking the one electrode and the other electrode via a separator, the electrode group being housed with an electrolyte inside the outer can; a current collector joined to the one electrode of the electrode group; and a current collecting lead interposed between the sealing body and the current collector and joined to the sealing body and the current collector to electrically connect the current collector and the sealing body, characterized in that the current collecting lead has a top wall located on a side of the sealing body, a bottom wall facing the top wall and located on a side of the current collector, and a pair of side walls extending between a side edge of the top wall and a side edge of the bottom wall, and facing each other, and the top wall is divided by a top wall slit extending along a long side direction and includes one divided first half body part and one divided second half body part including faced parts (52c and 54c) facing the bottom wall, and extension parts (52a, 52b, 54a and 54b) extending outward from the faced parts (52c and 54c), the extension parts (52a, 52b, 54a and 54b) being joined to the lid plate, wherein the extension parts (52a, 52b, 54a and 54b) have a welded part including a portion in which a lead protrusion formed out of the top wall by punch press processing protruding to the side of the sealing body is deformed by heat and wherein the current collector has a welded part including a portion in which a current collector protrusion formed out of the current collector by punch press processing protruding to a side of the current collecting lead is deformed by heat.