The purpose of this study was to explore the mechanism involved in predicting the Quality of Life (QOL) of middle.aged Koreans. The QOL was measured by integrating life satisfaction indicators. To accomplish this, a survey data set was drawn from a convenient sample of 670 individuals during the period of January and February 2011. To differentiate the influences from the different life domains, stepwise multiple regressions were attempted. In our results, the SES indicators, personal mental health, physical health, social capital resources from family as well as job places, perceived local government services, and the current living conditions to determine QOL, explained 55% of the total variance. In conclusion, the results of this study demonstrated the complex mechanisms that explain QOL in terms of ecological predictors.