An energy storage device includes a casing, a power generating element, a current collector, a connection conductor, an external terminal, and a rivet. The energy storage device further includes a welded portion where at least one of a contact portion between a casing inner portion of the rivet and the current collector, a contact portion between a casing outer portion of the rivet and the connection conductor, and a contact portion between the connection conductor and the external terminal is welded at least partially.