Compliance with the professional ethics of the internal auditor is one of the most important factors that leads to an increase in the quality of the auditor's work through individual conscience. One of the factors that is affected by the professional ethics is the improvement of the control environment. Consequently, the aim of the research is to enhance the improvement of the control environment by using the principle of observing the auditor's personal professional ethics. Data collection was done using the internal audit reports issued by the auditing institutions that are members of the Certified Public Accountants Society of Iran during the period of 2009-2019. The sample size was selected based on the researcher's access to the internal reports of the auditing institutions and members of the public accountants community of Iran. Based on this, 76 companies affirmed by the stock exchange with internal auditors were selected. Also, data analysis was done by using least squares regression, in the light of the regression assumptions. The evidence indicates that the quality of human resources working in internal audit, except for the experience of the head of internal audit, the type and level of internal audit reporting, the size, independence and status of internal audit, the performance of internal audit due to the lack of membership of the CEO and the presence of a financial expert tend to have consistent effects on the enhancement of the control environment. However, the experience of the head of internal audit, the interaction of internal and external auditors, the effective combination of non-commissioned managers in the board of
directors, and the distinguishing the duties of the CEO from the head of the board of directors, do not have a significant effect on improving the control environment.