Molecular arrangement of polymerizedn-octadecyltrichlorosilane (OTS,CH3(CH2)17SiCl3)monolayertransferred onto hydrophilic substrate by an upward drawing method wasinvestigated with a transmissionelectron microscope (TEM) and an atomic force microscope (AFM).The electron diffraction (ED) patternof the OTS monolayer revealed that the OTS molecules were regularlyarranged in a hexagonal array witha (10) spacing of ca. 0.42 nm. The high-resolution AFM image ofthe OTS monolayer in a scan area of 10× 10 nm2 exhibited the individual methyl group of whichpacking was a hexagonal array in a similarmolecular arrangement concluded on the basis of the ED study.Also, the point defect in the crystallineOTS monolayer was successfully observed for the firsttime.