Abstract: A thin-layer magnetic field sensor in which a thin magnetic layer which is magnetized in a preferred direction is surrounded by a magnetic HF measuring coil with variable inductance and in which an external magnetic field and the coil axis are aligned so as to be parallel to one of the preferred directions. The sensor comprises a sequence of geometrically structured layers arranged on a substrate, i.e. a structurized metal electrically conducting layer, a dielectric layer, a magnetic layer magnetized in a preferred direction, a further dielectric layer and a further structurized metal electrically conducting layer which forms with the first electrically conducting layer a coil which surrounds the magnetic layer.