Disclosed herein is a planar magnetic element comprising a substrate, a first magnetic layer arranged over the substrate, a first insulation layer arranged over the first magnetic layer, a planer coil formed of a conductor, having a plurality of turns, arranged over the first insulation layer and having a gap aspect ratio of at least 1, the gap aspect ratio being the ratio of the thickness of the conductor to the gap between any adjacent two of the turns, a second insulation layer arranged over the planar coil, and a second magnetic layer arranged over the second insulation layer. When used as an inductor, the planar magnetic element has a great quality coefficient Q. When used as a transformer, it has a large gain and a high voltage ratio. Since the element is small and thin, it is suitable for use in an integrated circuit, and can greatly contribute to miniaturization of electronic devices.