In the field of ergonomics, it is evident that participatory action research methodology could contribute to reduce risk factors of work related musculoskeletal disorders(WMSDs). The objective of this study was to evaluate the effectiveness of a participatory ergonomics in reducing the incidence rate and severity of WMSDs in the tire manufacturing company. In this study, an action committee comprising 13 members was organized in the tire manufacturing company. The action group participated at every research process, education and training, assessment and intervention of risk factors, and early detection and management of WMSDs during the 3 years(2004-2006). The prevention programs contributed to an overall reduction in incidence rate by approximately 37.2%, and lost workdays and workers` compensation costs by approximately 55.1%. But, the incidence rate increased 29.0%, and compensation costs increased 59.0% in the first-year setting programs, and both the incidence rate and compensation costs decreased after the second-year managing programs. And, the reduction rates(63.2%) of insurance cases is higher than that(9.7%) of non-insurance cases. The results showed that participatory ergonomics programs may be effective in reducing the incidence and severity rate of WMSDs.