The study deals with automatic path planning method for cutting operation using an industrial robot. In general, studies of motion planning for industrial robots are divided in two approaches, considering a robot configuration or a tool configuration. However, in case of cutting operation using an ultrasonic cutter, generation of optimal tool path becomes difficult, because it is required consideration of continuous tool posture, wide movable range of robot, and high tool feed speed. In this study, we propose the use of an original local configuration space that generated by two angles that determine tool posture at each cutting point, and generate tool path using an A-star search algorism based on the evaluations of interference, movable range and mobility of robot that varied according to relationship of tool feed speed and angular speed of each joint. As a result, it is found that the proposed path generation method is more effective than conventional methods.