Refer to CMMI-Institute Appraisal result, there are 6 (six) companies in Indonesia that have achieved CMMI-Dev v1.3 maturity level 3, one of them is XYZ Corporation. Initially, XYZ Corporation has set a target to achieve CMMI-Dev level 2. As advised by the consultant, XYZ Corporation has a possibility to achieve level 3 by completing several parts of level 3 requirements that had not been met yet. XYZ Corporation faced a significant problem in progress implementation, particularly in documents standardization. This is due to each division has a different document format. XYZ Corporation also needs to improve its current processes that are still in ongoing phase of improvement process to achieve better standardized. This research aims to find out "The factors that affects the success of CMMI-Dev implementation based on its Current Conditions of XYZ Corporation". The approach of this research in finding the factors that influence the implementation of CMMI-Dev by means Qualitative and Quantitative approach. A qualitative method, by means of questionnaires, is used to prioritize the main factor. A quantitative method is used to get ranking of the factors that affecting successfulness of CMMI-Dev implementation in which has been validated by questionnaire's results. This research finding expects that the factors could be applied by other companies which desire to implement CMMI-Dev.