The study deals with the automation of polishing process for free-form surfaces by means of an industrial robot. In general, the polishing process has been performed by handwork of skilled workers. Since the polishing environment is extremely inferior and the polishing process is time-consuming and tedious work, the automation of polishing process is strongly desired and the robot systems have been introduced recently. However, the polishing by robots has not necessarily been performed in success. In the study, the polishing path generation is devised to improve the surface quality of workpieces. Thus, the relationship between the surface curvature of workpiece and the contact length of polishing tool is investigated by polishing experiments, which results in the new polishing path generation method. The method is successfully applied to polish an impeller of food and osmetics agitators, which consists of free-form surfaces. As a result, it is found that the new polishing path generation method is effective for polishing automation by robots.