The operation and maintenance phase is one of the most important and longest phase in the green building life cycle. In this phase, the existence of internal support and facilitating that is oriented towards sustainable green management can have a major impact on building performance. Its existence is both a support and a catalyst for other processes to be undertaken during this phase. This study aims to assess the content validity in the preparation of a questionnaire for the assessment instrument for internal support and facilitating of sustainable green management, particularly the operation and maintenance phase of buildings in Indonesia. Internal support and facilitation is divided into 3 key variables in this research: leadership, policy, and people. Meanwhile, the study stage consists of instrument design, expert panel determination, and content validity quantification. The method used in the content validity analysis consists of: I-CVI, S-CVI, CVR and Kappa statistical coefficient. Based on the results of the study, the number of indicators that meet the requirements is as follows: four indicators on the leadership variable, six indicators on the policy variable and five indicators for the people variable.