The current study aims to investigate the relationship between internal audit and the characteristics of the board of directors in companies listed on the Tehran Stock Exchange, which was carried out in 1401. The research method is descriptive-survey type. The statistical population of the present study includes companies in the west of the country that have internal audits, a total of 600 companies, and a questionnaire was sent to their heads of internal audit, and a total of 280 questionnaires were received. To explain the hypotheses of the research, the inferential method of the t-test was used based on SPSS statistical software. The characteristics of the board of directors in this article include the percentage of independent members of the board of directors, the dual role of the CEO, the gender of the board of directors, and the size of the board of directors. The results indicated that there is a positive and significant relationship between internal audit and the characteristics of the board of directors in companies listed on the stock exchange.