The invention provides a power storage device having flexibility, a power storage device of which the capacity is not likely to deteriorate even when being curved, a large-capacity power storage device, and a small-sized power storage device. In an embodiment of the invention, the power storage device includes a first electrode, a second electrode, and an electrolytic solution. The first electrode is used as one of positive and negative electrodes and the second electrode is used as the other of the positive and negative electrodes. The first electrode and the second electrode overlap with each other. The first electrode includes a first current collector and a first active material layer. The first current collector has a first surface and a second surface. The first active material layer is provided on the first surface. The first current collector has a first bent portion with the second surface inside. The second surface includes a first region and a second region. The first region overlaps with the second region. The first region is connected to the second region at a portion different from the first bent portion.