The purpose of this study is to present the psychological capital as a leading factor affecting organizational commitment, to determine the role of job satisfaction as a mediator among those, and finally to find the way to increase the commitment by suggesting a new idea for human resources management in the foodservice firms which were having difficulties in finding new employees and in high turnover rates. A survey was conducted on the employees in foodservice firms including both franchise management and direct management restaurants for the period of the month of February 2012, and the data were analyzed with frequency analysis, reliability test, exploratory factor analysis, confirmatory factor analysis, correlation analysis, path analysis, and mediating effect analysis by using SPSS 15.0 and AMOS 7.0. As a result of the study, the psychological capital factors such as hope, resiliency, and optimism had significant effects on organizational commitment, and job satisfaction strongly mediated the relations of the psychological capital factors as presented above and the organizational commitment.