A multilayered device comprises an insulation sheet 1 having at least two foldable areas 11, 12 which are multilayered by being folded; and a first conductor 21A, 22A which is formed on a first face 11A, 12A and constitutes a first coil 51A, 52A having one turn or more, and a second conductor 21B, 22B which is formed on a second face 11B, 12B and constitutes a second coil 51B, 52B having one turn or more in the same winding direction as that of the first coil in each of the foldable areas, at least four conductors are disposed in parallel with each other by folding the insulation sheet so as to constitute an inductor, and thus, it enables to thin the thickness of the multilayer, to downsize and to lightweight even when it constitutes a coil device having a larger winding number.