To provide an electrode for a power storage device, which has high reliability and can be miniaturized. To provide a power storage device including the electrode. In the electrode, a stress-relieving layer which relieves internal stress of an active material layer including a whisker is provided over a current collector. By the stress-relieving layer, deformation of the current collector can be suppressed and the productivity of the power storage device can be increased. In addition, the size of the power storage device can be reduced and the reliability thereof can be increased. Graphene may be formed so as to cover the active material layer including a whisker.