The main aim of this research is to identify the role and activities of internal auditor in achieving corporate sustainability for listed corporations in the stock exchange under the pressure exerted by international and professional organizations on the compatibility between their economic objectives, social and environment requirements and improve their relationship with several parties as a prerequisite for survival and continuity and also how the role of internal auditor in corporation affect the stakeholders decisions generally and how such a role regarding sustainability affect also their decisions -in indirect way- specially the decisions of their investment in those corporations.