We demonstrate here the microlithography of a thin chromium film on a quartz plate by using an atomic force microscope (AFM). Langmuir-Blodgett (LB) films of omega-tricosenoic acid were examined as resist films. By scanning an AFM tip under a high normal force, the omega-tricosenoic acid LB film deposited on the chromium film was scratched out. By the further use of wet etching of the chromium film, the process of submicrometer-scale lithography was demonstrated. Protection of the chromium film against etching by the use of multilayered LB films is discussed in terms of the probability of formation of tunnel defects entirely across the LB film.