To provide a means by which an electrical device such as a lithium ion secondary battery that has a positive electrode using a solid solution positive electrode active material can be provided with satisfactory performance in terms of rate characteristics while sufficiently making use of the high capacity characteristics that characterize solid solution positive electrode active materials.An electrical device that has a power generating element containing a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on the surface of a positive electrode current collector, a negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on the surface of a negative electrode current collector, and a separator, in which the coating amount of the negative electrode active material layer is 3 to 11 mg/cm2, the negative electrode active material layer contains the negative electrode active material represented by the formula (1), the positive electrode active material layer contains the positive electrode active material represented by the formula (2) (solid solution positive electrode active material), and, as a solid solution positive electrode active material to be contained in the positive electrode active material layer, the material having composition represented by the formula (3) is used.