An electricity storage device is provided with an electrode assembly with a structure such that positive electrodes and negative electrodes are alternately stacked while the positive electrodes and the negative electrodes are insulated from one another. Tab groups including positive electrode tabs and negative electrode tabs gathered in the stacked direction of the electrode assembly are disposed on an end of the electrode assembly. The tab groups include a first bent portion which is curved or bent, and an extension portion extending from the first bent portion in the stacked direction of the electrode assembly. The tab groups also include a second bent portion at which the tab groups are curved or bent such that the front end in the extending direction of one of the tabs positioned on the outer-most peripheral side at the first bent portion is positioned between the electrode assembly and one of the tabs that is positioned on the inner-most peripheral side at the first bent portion.