This study reviews and modifies general IS success models to find success factors of WIS(Web-based Information Systems) and to confirm the relationship between WIS success and user's satisfaction of web use. A WISSM(Web-based Information Success Model extended to include EQ(E-Quality) is developed to anticipate user's intention to use Web-based Agricultural Information System and fit into the survey data from 252 WIS users of RDA(Rural Development Administration). PLS is applied to estimate a structural model based on EQ-WISSM to test hypotheses including 1) users reach a high level of intention to use Web-based Information Systems when they feel a high level of interactivity among an 'E-Quality', 'Decision Making Support Satisfaction' and 'Task Support Satisfaction', and E-Quality boosts intention to use Web-based Information Systems. The results show high path coefficients and R2 values and find followings; First, the EQ-WISSM explains the user's intention to use WAIS quite well. Second, E-Quality can be used well in web-based IS environment to predict IS Success. Finally, this research finds the importance of 'Task Support Satisfaction' as a mediator between 'Decision Making Support Satisfaction', 'E-Quality' and 'Intention to Use'.