Specimen preparation is always a crucial question of transmission electron microscope (TEM) investigation Recently new specimen preparation technique using focused ion beam (FIB) milling was developed. We applied this technique to the fabrication of cross-sectional TEM specimens of industrial materials including heterointerfaces. The following investigations were carried out: multilayered structures in thin-film transistors for the liquid crystal display, interfaces in a hot dip galvanized steel and microstructures of a diamond Nm on silicon nitride. The largest benefit of FIB lies in its application to heterointerface analysis at a particular position in submicron scale. This technique extends the use of TEM analysis into new areas of. characterization of ind;strial materials.