As the audit tenure increases, the quality of the audit also increases, as a result, the uncertainty of information decreases. The audit quality affects the information asymmetry between traders, which results in an increase in the quality of the company's financial reporting and ultimately a reduction in agency costs in the company. The purpose of this research is to study the effect of business continuity risk on the relationship between auditor tenure and agency costs. The statistical research population of companies admitted to the Tehran Stock Exchange and the studied sample includes 140 companies admitted during the years 1396 to 1400. The research method is descriptive and in terms of the relationship between the variables, it is a combination of causality-correlation, and it is practical in terms of the goal. The regression method and panel data as well as the fixed effects model were used to process and test the hypotheses. The results of the analysis of the research model showed that the risk of continuity of activity has a negative and significant effect on the relationship between the tenure of the auditor and agency costs.