Introducing technological trends in small case size metal type power inductors, according to the higher switching frequency, the required inductance value has become lower and the replacement of materials from ferrite to metal has progressed. The small metal type power inductors have various types of metal magnetic materials (resin composite type, oxide layer bounded type) and structures (wire winding, thin film and multi-layer type), and each type has been developed actively. The directions of development are higher current and lower loss. Therefore, the developments of the structures and the magnetic materials, such as high packing of magnetic powders, specific performances of magnetic powder materials and particle size reduction, have been in progress.