The purpose of this study is ranking the factors affecting auditing risk with the TOPSIS technique. The population of this study was members of Iranian Association of Certified Public Accountants. These members are included in 4 groups. CPAs that are partner of auditing firms, CPAs that work in Audit Organization of Iran, CPAs that work as the member of audit firms and CPAs that work individually.For ranking factors affecting auditing risk, by conducting archive study and interview with 22 CPAs as a pilot study, 56 factors were identified for inherent risk, control risk and detective risk. These factors were presented in the first questionnaire with five- option Likert spectrum. Factors that their averages were higher than the average of the index were selected as the internal factors for the second questionnaire. The number of factors that selected from the first questionnaire was 30 and were presented in paired comparisons situation. Then, second questionnaire was distributed among 4 groups of the Iranian Association of Certified Public Accountants. Consequently, the data from the second questionnaire was analyzed with the TOPSIS technique, and effective factors on auditing risk, were ranked from every 4 groups of the CPAs and for every risk index.The result of this study showed that from viewpoint of the 4 groups of Iranian Association of Certified Public Accountants, factor of “entry and asset adequate protection” with the relative proximity of 0.970 is the most potent factor for decreasing the auditing risk. Also, factors of “accounting systems effectiveness” and “the internal audit unit function” with the relative proximity 0.965 and 0.963 respectively are in the second and third position. These findings indicate that the Audit Organization of Iran must pay attention to risk factors identified by this study and promulgate the special standards relating to audit risk. In addition, auditors, financial managers, internal auditors and Tehran Stock Exchange Market of Iran must encompass the identified risk factors of this study in their professional decision makings.