It is important for atomic layer control to carry out in-situ analysis of the topmost atomic species and structure. Although RHEED (Reflection High Energy Electron Diffraction), AFM (Atomic Force Microscopy) and XPS (X-ray Photoelectron Spectroscopy) are considered to appropriate methods for this purpose, each method is not sufficient enough to obtain necessary information. Recently several papers describe that CAICISS (Coaxial Impact Collision Ion Scattering Spectroscopy) is appropriate to in-situ analysis for an atomic layer control. This analyzer was applied to observations of topmost atomic planes of several crystals such as SrTiO₃, GaAs, InP and SiC. As a result, the topmost planes of these crystals were analyzed successfully for atomic layer control. Therefore, we introduce these applications and discuss the possibility of atomic layer control by in-situ CAICISS analysis in this paper.