A semiconductor structure provided with an insulation structure in a moving unit is manufactured easily. In the case that the document tray is located not at the highest position, not at the lowest position, but at a middle position upon powering on the power source, the document tray is allowed to remain at the middle position as it is without performing the elevation of the document tray. The magnetic layer is composed of a plurality of layers of Co-based alloy of hexagonal close-packed structure which are antiferromagnetically coupled to one another through a non-magnetic intermediate layer, said three underlayers including an amorphous alloy layer, a Ta layer, and a Cr-based alloy layer of body-centered cubic structure.