In service science, it is critical to measure service satisfaction for innovating service processes, which is challenging for service sectors oriented to the usage of IT systems. For that purpose, in this study, a model based on the technology acceptance model and satisfaction measurement model is proposed. The model is empirically tested using data sets from a public service sector (G2B) and a private service sector (internet banking). The purpose of this study is to identify factors which affect the service satisfaction. The result shows that a public service sector is less sensitive to the IT systems on which its services are operated, and that the attitude factor strongly affects the service satisfaction in both sectors.