Financial reporting and its quality has been one of the concerns of investors and shareholders. In this regard, one of the factors that can be useful in improving the financial reporting process is the existence of internal audit. The present study examines the impact of the internal auditor on the quality of financial reporting with emphasis on the role of the audit committee. This research is applied in terms of purpose and in terms of correlation methodology is causal (post-event) research. All companies listed on the Tehran Stock Exchange were the statistical population of the study. Using a series of restrictions, 122 companies were selected and surveyed over a period of 6 years between 1392 and 1397. The method used is data collection, library, and multiple linear regression is used to test the hypotheses. Stata software version 15 was used to perform tests and final estimation of models. The results show that the internal auditor has a direct and significant effect on the quality of financial reporting. The existence of an audit committee strengthens the direct impact of the internal auditor on the quality of financial reporting.