Managing knowledge effectively would bring great benefit to the organization. However, there is a challenge to manage the knowledge since most of them still in tacit form. Thus, the knowledge management system is a solution for managing the knowledge in an organization to make the most of it. Since 2013 the Ministry of Communication and Information Technology has developed a Knowledge Management System (KMS). Following the socialization, the socialization of the system, the number of users who involve in KMS reached 260 users (13.2% of all employees); however, this condition has not met the expectation since the system was considered a strategic application. Therefore, this research was conducted to find out the factors that influence the acceptance of KMS in government organizations. To answer this question, the authors form a research model with the UTAUT2 model and the IS Success Model. Questionnaires were distributed, and 83 data then analyzed using SmartPLS v.3.2.7. The results found that factors influencing the intention to use KMS were system quality and information quality from the IS Success Model and habit from UTAUT2. Because KMS is only used voluntarily by the employee, it is the quality that will influence user intention. The system capability drew users instead of out-of-system factors such as user expectation and habit. Thus, improving system quality and information quality will increase the use of KMS in the future.