Potential-induced self-organization of alpha-cyclodextrin (CyD) on Au(111) surfaces in sodium perchlorate has been investigated by using in-situ scanning tunneling microscopy (STM). Near the open circuit potential (approximately + 0.0 V vs. SCE), the CyD molecule adsorbs randomly on bare Au(111) surfaces and the desorption of CyD from Au surfaces is observed at negative potentials less than - 0.40 V. On the other hand, it was found that the CyD molecules formed an ordered array with a cylindrical structure on the Au(111) surface in the potential region from - 0.20 to - 0.15 V. The cylindrical structure in which the cavities of CyD race sideways proved that the structure of the adlayer is formed not by simple epitaxy but by self-organization of the molecules.