At least one electric power storage device that is cylindrical, an upper holder holding the at least one electric power storage device, an insulating plate provided above the upper holder are included. An exhaust valve is provided on the upper end part of the electric power storage device, the upper holder includes an opening part for exposing the exhaust valve, the insulating plate includes a flat plate-shaped main body part, an opening part formed on the main body part and communicating with the opening part, a lid part closing a part of the opening part, and a connecting part that connects the lid part to the main body part. The main body part includes a fixation part for fixing the insulating plate and the upper holder.