The overlayer structure of [tetra-(3,5-di-tertiary-butylphenyl)porphyrinato] copper (Cu-TBPP) molecules on Ag (001) and chloro(subphthalocyaninato)boron (III) (SubPc) molecules on Ag (111) were analyzed by a UHV scanning tunneling microscope. In the case of approximately 20% coverage, both molecules showed high mobility on the substrates, which caused them to form an overlayer island on terraces. Cu-TBPP molecules formed an oblique lattice on the Ag (001) surface and SubPc molecules formed a hexagonal lattice on Ag (111). From a high-resolution STM image of the overlayer, characteristic protrusion corresponding to the molecular shapes, such as four-lobes of Cu-TBPP and three-lobes of SubPc, were clearly identified.