Recently, a convenient wet-chemical treatment method to terminate silicon surface with hydrogen atoms has been developed. It is attractive from the viewpoint of surface science and device technology. However, since the atomic structure and surface microroughness of the surfaces treated by the wet-chemical process is strongly affected by the condition, we should optimize the treatment condition in order to make atomicallyflat and well-ordered hydrogen-terminated surface. Here we discuss the optimization of wetchemical treatment of the hydrogen-terminated Si(111) and (001) surfaces.