PT. Bank Sayiah Indonesia is one of the BUMN branch offices, which must implement Good Corporate Governance in accordance with GCG principles set forth by the Minister of SOEs PER-01/MBU/2011. Internal Audit is one of the elements in GCG and has a role in overseeing the implementation of management and supervision of the company all practices undertaken by the company. The implementation of GCG in banks must follow OJK rules and follow GCG guidelines by KNKG. Therefore, this study aims to determine the implementation of GCG in the bank and determine the role of internal audit in realizing GCG implementation. This type of research is descriptive qualitative. The method of analysis used in this study is a descriptive method with data collection techniques such as interviews, observation and documentation. The results of this study are Islamic banks Indonesia has implemented GCG in accordance with applicable rules is by applying GCG principles. In addition, internal audit works in realizing GCG implementation of Bank Syariah Indonesia.