Electric storage device

An object is to provide an electric storage device capable of preventing an inner-circumferential end portion of a negative electrode and an inner-circumferential end portion of a positive electrode from moving in the space at the winding center of an electrode assembly. An electric storage device includes an electrode assembly, in which a positive electrode and a negative electrode in the shape of a sheet are wound with a separator sandwiched therebetween. The electrode assembly has a flat shape and includes a first flat portion and a second flat portion, which are opposed to each other, and a first curved portion and a second curved portion which connect end portions of the first and second flat portions together. One of the positive electrode and the negative electrode covers an inner-circumferential end portion of the other electrode and is disposed on an innermost circumference of the electrode assembly. An inner-circumferential end portion of the one of the electrodes causes an elastic force to act outwardly on the other electrode.