The positive electrode substrate exposed portions or the negative electrode substrate exposed portions, or both, of an electrode assembly is split into two groups, and therebetween is disposed an intermediate member made of a resin material and holding one or more connecting conductive members. Collector members for the substrate exposed portions split into two groups is electrically joined by a resistance welding method to the substrate exposed portions split into two groups, together with the connecting conductive member(s) of the intermediate member. The resin material portion of the intermediate member protrudes, in the extension direction of the substrate exposed portions split into two groups, beyond the ends of the substrate exposed portions split into two groups and the ends of the collector member to a prismatic outer can. This structure enables enhanced resistance between the substrate exposed portions and the collector member and curbs variation in the welding strength.