Strategic deviation in companies refers to the fact that the company's strategy in the process of organizational integration has deviated from the industry trend. Many companies are not separated from the main trend of their industry, while some companies have deviated from this main trend in the process of industrial integration. This category of deviation from the main trend of the industry is called strategic deviation. The purpose of this research is to examine the effect of managers' narcissism on the company's strategic deviation from the industry with an emphasis on institutional ownership. The present study is applied in terms of implementation results and correlational in terms of methodology. The sample of the present study includes 125 companies listed on the Tehran Stock Exchange for the years 1396 to 1403. Multivariate regression with composite data has been used to test the research hypotheses. The results of the hypothesis test showed that managers' narcissism has a positive and significant effect on the company's strategic deviation from the industry. In other words, the greater the managers' narcissism, the greater the company's strategic deviation from the industry. Also, institutional ownership weakens the effect of managers' narcissism on the company's strategic deviation from the industry.