The cycle performance of a lithium-ion secondary battery or a lithium-ion capacitor can be obtained by minimizing the decomposition reaction of an electrolytic solution, etc. in the repeated charge and discharge cycles of the lithium-ion secondary battery or the lithium-ion capacitor. An electrode includes a current collector and an active material layer over the current collector. The active material layer includes active material particles, a conductive additive, a binder, and a film containing silicon oxide as its main component. The surface of one of the active material particles includes at least one of a region in contact with the surface of another active material particle, a region in contact with the conductive additive, and a region in contact with the binder. The surface of the active material particle except these regions is at least partly in contact with the film containing silicon oxide as its main component.