Warranty of quality in industrial products depends on to confirm everything on their production process. There are some cases in assemble process that the process itself satisfies the regulation or not is very difficult. For example, to fix a part by using some bolts, order to screwing is often regulated to guarantee accuracy to attach the part. However, once it is fixed, even if the procedure is violated as long as screws are enough fastened, thus accuracy is not guaranteed and the violation cannot be detected. So we are developing a system that monitors worker's motions in routine works in factory, employing terrestrial magnetism and acceleration sensors. In this system, these sensors are attached onto tools, and the system judges the work is correctly done or not. In this paper, we describe a method to judge which uses Local Outlier Factor (LOF), and we show some evaluations on automobile assembly factory.