ENERGY STORAGE DEVICE AND METHOD OF MANUFACTURING ENERGY STORAGE DEVICE

An energy storage device is equipped with a container having a container body and a lid body, which closes an opening of the container body. An elongated welded part which is a welded portion between the container body and the lid body, is formed on the container. The welded part has a first welded part and a second welded part arranged in a row in a lengthwise direction of the welded part, wherein a width of the second welded part in a widthwise direction of the welded part is set larger than a width of the first welded part in the widthwise direction. A gas release vent is disposed on the lid body, wherein the second welded part is disposed on a lateral side of the gas release vent, and a length of the second welded part in the lengthwise direction is set larger than a length of the gas release vent in the lengthwise direction.