The greater the level of corruption in a society, the greater the justification for immoral actions and behaviors. Therefore, companies that operate in highly corrupt environments face a weaker financial reporting system. This study aims to investigate the effect of financial Corruption on internal control quality. Thus, we have applies Corruption Perception Index and accountability as indexes of financial Corruption, and also in order to measurement the internal control quality we have taken internal control material weaknesses. Tehran stock exchange listed firms constitute statistical population of the research and the sample was selected imposing conditions of the research variables to 161 firms during 2012-2021. Due to the nature of the dependent variable and the homogeneity of the sample, Logit regression method is used to test the hypotheses. The results also show there is a significant relation between the Corruption Perception Index and internal control quality.Also, the results showed that the higher the accountability index, the lower the weakness in internal controls. The results of the research can draw the attention of legislators and shareholders to the importance of the issue of corruption and take the necessary measures to identify and prevent corruption actions at the level of companies.