This study aims to propose an evaluation model for public sector information systems used under involuntary conditions. To this end, based on discussions of the information systems success models (IS success model) by DeLone and McLean (1992, 2003) and Seddon (1997), factors capable of capturing the characteristics of involuntary information systems were explored. These factors were then incorporated into the IS success model to present a revised and improved evaluation model. The analysis results confirmed that the model fit was at an acceptable level for most indices, and the relationships among constructs were analyzed as follows. First, among the exogenous variables, system quality and service quality were found to have a positive effect on system usage or satisfaction, while facilitating conditions were confirmed to have a positive relationship only with system usage. Second, system usage and satisfaction were found to have a positive effect on net benefit, which is the goal of information systems. Third, under involuntary environments such as the public sector, system usage was found to have no relationship with satisfaction. These research findings provide not only theoretical implications for improving the IS success model but also empirical implications regarding which aspects organizations should focus on when operating information systems.