We have investigated the atomic hydrogen (H)-surfactant mediated growth of Ge on Si(111) surface, using coaxial impact-collision ion scattering spectroscopy (CAICISS), time-of-flight elastic recoil detection analysis (TOF-ERDA) and scanning electron microscopy (SEM). It has been found that the Ge thin film on the Si(111)1 x 1-H surface is flattened by the H-surfactant, whilst on the Si(111)7 x 7 surface the flatness does not change in spite of supplying H. These results indicate that the flatness of the Ge thin film is strongly influenced by the structure of the Si(lll) substrate surface at the initial stage of Ge thin film growth.