Today, many researchers investigate extensively the molecular arrangement techniques for various organic materials at a nano meter scale in order to fabricate the organic thin films with novel electronic and photonic functions. For achieving this purpose, it is most important to understand the mechanism of molecular orientation during a film growth process. Thus, it have been strongly desired to develop the measuring system, which enables us to evaluate the crystal structures and molecular orientations of organic ultra thin films during the growth process. For inorganic materials, structural observations of the films grown by a molecular beam epitaxy (MBE) technique are generally conducted by using a reflection high energy electron diffraction (RHEED) method. But, this method can not be applying for many organic thin films because an electron beam destroy them. Since the organic molecules are stable to the x-rays, x-ray fluorescent and diffraction methods are suitable for such investigations of organic thin films.