Sriwijaya University (Unsri) as one of the state higher education institutions should be able to utilize information and communication technology in supporting various activities, one of which is in the learning process activities. One of the uses of information and communication technology at Sriwijaya University is by using an academic information system named Sistem Informasi Manajemen Akademik (SIMAK) of Sriwijaya University (Unsri). SIMAK is a mandatory system developed in 2008 to support academic activities in Unsri. Unsri has never evaluated the success factor of using SIMAK. Because it is a mandatory system, the success in carrying out academic activities depends on SIMAK application, so the researcher want to know what factors affecting the success of SIMAK usage on lecturer users. The research model used is a modification of DeLone and McLean information system success theory by adding several variables from individual aspects and organizational aspects. Data collection through a survey of 1232 lecturer respondents who were SIMAK users. The research method used is the mixed method. Structural Equation Modeling (SEM) is used to analyze data and SmartPLS as data processing tools. The results indicate the factors that affecting the successful use of SIMAK, namely information quality, service quality, system quality, self-efficacy, top management support, user satisfaction, and net benefits.