Process safety incidents and loss events can be prevented if we identify and adequately take measures on process safety incident precursors in a timely manner. If we look into and take action against the process safety hazard factors causing the incident in the refinery and petrochemical plant, major process safety incidents can be prevented through eliminating or decreasing hazardous factors. We conducted a survey for the major process safety incident precursor to look specifically into the potential process safety hazardous factors of refineries and petrochemical plants in the Yeosu chemical complex. A self-assessment checklist, which was published by Center for Chemical Process Safety “Recognizing catastrophic incident warning signs in the process industry” on major incidents warning sign, was used for the survey. Through this survey, the major process safety incident leading indicators in the process industry were found by process safety management elements, and each site and/or facility can use these leading indicators for activities for process safety incident prevention. In addition, we proposed action items required to eliminate the root cause of those process safety incident leading indicators.