Abstract:The information system auditing is conducted to evaluate the readiness level of organization in managing information technology (IT). This research is conducted in library of Petra Christian University, Indonesia. In this academic institution, the library has already used IS to accommodate in its business processes. Library has done the observation to measure library users' satisfaction toward library service. In this previous observation, it has been found that the library software is not satisfied the students, lecturers and staffs as the users in providing information. Furthermore, the initial observation had found out that a lot of misinformation because human errors have often occurred in inputting data and monitoring and evaluating of library software performance has not been. Best practice is given using CMMI standard which is obtained by mapping IT processes of COBIT. Results of audit that has been conducted provide the current maturity level is level 2-managed which means the performed process have ensured that requirements are managed and executed in accordance with policy. Organization has understood the importance of managing IT in helping business processes. System development procedure has been documented. System is a form of elaboration formalization of existing activities and made it easier for users to learn to control quickly.