One embodiment of the present invention is an electricity storage element comprising an electrolytic solution, an electrode body obtained by winding a strap-shaped positive electrode that has a positive electrode active material layer, a strap-shaped negative electrode that has a negative electrode active material layer, and a strap-shaped separator in the longitudinal direction, and a container that accommodates the electrode body and the electrolytic solution, wherein: at least one of the positive electrode active material layer and the negative electrode active material layer have hollow active material particles; the winding axis of the electrode body is disposed parallel to the horizontal direction; at least the center part of the electrode body is in a pressed state by the container being compressed; excess electrolytic solution that is a part of the aforementioned electrolytic solution is present between the electrode body and the container; the bottom end of the electrode body is in contact with the excess electrolytic solution; and the relationship between the height H from the liquid surface of the excess electrolytic solution to the top end of the electrode body and the width Wc of the positive electrode active material layer fulfills formula (1). Formula (1)...0.8 H≤Wc≤2.0 H