Due to several medical accidents breaking out, patient safety is getting more emphasis. People have raised attention to human factors (ergonomics) approach to improve patient safety. The purpose of this study is to evaluate the situation of human factors intervening medication for patient safety improvement cases and provide the advanced human factors knowledge to medication in hospitals and to reduce the risk of human error in hospitals. The cases are from Taiwan Joint Commission on Hospital Accreditation (TJCHA) collected from hospitals. The cases have been reorganized by the domains view of ergonomics; graded by the level how they approach of ergonomics and quantified to do statistical analysis. The results shows that percentage distribution of ergonomics knowledge using for medication safety promotional are physical ergonomics (5.41%), cognitive ergonomics (21.62%) and organizational Ergonomics (72.97%). Some recommendation for increasing medication safety have been presented to all levels of medical institutions for reference study.