A kind of hiyarihatto activity where workers report incidents on their works and discuss them, has been introduced to industrial fields to cultivate safety attitude of participants. However, Computer Mediated Communication (CMC) hiyarihatto activity is not always active. The purposes of this study are to propose a method for promoting CMC hiyarihatto activity and to practice the proposed method. The proposed method consists of following two methods. (1) Introduction of active participants who are requested to activate hiyarihatto activity and are hidden facilitators. (2) Introduction of Root Cause Analysis(RCA) form as a new way of reporting incident case to database for promoting thinking about incidents. The proposed method was practiced where 6 groups of 6 active participants and 30 normal participants who were working in nuclear power plants. The results showed that (a) Some groups were activated under the control of the active participants and their topics were about new knowledge of incidents, (b) Participants could submit incidents using RCA form without big problems, however it needs much time, and (c) The proposed method was practicable in actual work environment on condition of periods without regular facility inspections. However, ¡Èdiscuss new knowledge¡É should be added to the action guidelines and RCA form should be changed to easier way.