The invention provides a sealed battery which can guarantee conduction between a power generator and a cover body without generating a welding defect. A lithium ion secondary battery includes a battery container (7). The battery container (7) houses an electrode winding body, on which positive and negative electrode plates are wound via separators, together with a non-aqueous electrolytic solution. A positive electrode tab is bonded to a positive current collector ring (4) arranged at an upper side of the electrode winding body. A battery lid (18) to be a positive electrode external terminal is crimped and fixed to the battery container (7). The battery lid (18) has a diaphragm in which a cleaving valve (12) is formed. A coupling part is bonded to the diaphragm, and a stack lead (9) with a plurality of thin plates being laminated is bonded to the coupling part. In the stack lead (9), a total sum t of thicknesses of the thin plates is not more than a thickness T of the coupling part. Melting from the stack lead (9) to the coupling part by laser irradiation is optimized.