Process safety management (PSM) of chemical industries in Japan is based on small group activities, which is called the Japanese style management system depending on the quality of the operators, which is different from PSM in EU and US. In this paper, Japanese PSM style was examined firstly by investigating the articles on a magazine published by Japan Society for Safety Engineering (JSSE). The result of the investigation showed about 18 kinds of safety activities are extracted from the articles. These activities are categorized into three kinds of activity, which are the activity directly relevant to incident prevention, the activity activating individual activity and the activity activating more than two activities. To investigate the feature of Japanese Management style in detail, all safety activities of Mitsubishi Chemical Corporation are extracted and compared the elements corresponding to the purpose of these safety activities with the elements of Risk Based Process Safety by CCPS. Based on the result, Mitsubishi Chemical's framework of management system is developed.