American Petroleum Institute (API) proposed the first Risk Based Inspection (RBI) method for petroleum refinery industries in 1996. Since that time, the interest in RBI was growing also in Japan resulted that “RBM Specialty Study Committee” was built in High Pressure Institute of Japan (HPI) as the first Japanese study organization of Risk Based Maintenance (RBM) in 2001. HPI established two working groups in 2002to make Japanese version RBM guidelines. One is WG1 for basic standard of RBM and the other is WG2 for actual procedure of RBM. As the beginning, WG2 studied API Pub 581 mainly, especially Technical Module and made“Technical Module Handbook”in March 2004. Then WG2 studied the evaluation method of probability and consequence of failure and made “RBM Handbook” in March 2006. Following that, WG2 continues working to develop RBM Guideline by the end of March 2008.