A battery device comprises a nonaqueous electrolyte secondary battery provided with an electric power generating element and a pressing member which presses the electric power generating element in the stacking direction. The electric power generating element comprises: a positive electrode with a positive electrode active material layer of a positive electrode active material on the surface of a positive electrode collector; a negative electrode with a negative electrode active material layer of a negative electrode active material on the surface of a negative electrode collector; and a separator which holds an electrolyte solution. This battery device satisfies (1) 0.1