ELECTRIC POWER STORAGE DEVICE

An electric power storage device includes at least one electric power storage cell having a first end provided with a first electrode, and a second end provided with a second electrode; a first electrode bus bar that is disposed on a side of the first end and is connected to the first electrode; and a second electrode bus bar that is disposed on a side of the second end and is connected to the second electrode. The first electrode bus bar is provided with a connection line connected to the first electrode. The first electrode bus bar and the second electrode bus bar are joined to each other by ultrasonic joining. A joint portion between the first electrode bus bar and the second electrode bus bar is disposed at a position that is closer to the second end than to the first end.