The purpose of this study is to try to find the risk of roller(mixing mill) in working site. In order to achieve the purpose, accident analysis and survey was carried out. This analysis revealed that average of loss days is 334.3 by roller jamming accident and 229.2 by other causes. It means jamming accident entails serious bodily harm. According to our research, we realize that most of rollers have some risk of the jamming accidents. It is simply because the roll gap in the roller is not more than 10cm. It also does not meet minimum distance so as to avoid the risk for jamming accident by KS. Furthermore, 28% of rollers have only one switch and 40% of rollers have two switches operating emergence stop equipment so as to reduce the risk of jamming accidents. Therefore, we presume that it is very difficult to turn on the switch of emergence stop equipment when they confront the accident because most of engineers are working alone.