Background: Assessment of the patient safety competency is necessary for the growth of nursing and safe care profession as well as evaluation of the nurses' educational needs. To this end, valid and reliable tools are required. Aim:The present study was conducted to determine psychometric properties of the Persian version of the patient safety competency self-evaluation (PSCSE) tool in Iranian psychiatric wards. Methods: All nurses (n = 209) working in two psychiatric hospitals of Kerman, Iran were included in the present cross-sectional study using census method. Followed by administering the Persian version of PSCSE to the participants, its internal consistency and reliability were assessed by test-retest method with an interval of 14 days. Other psychometric properties such as content, construct, and convergent validity of the tool were also examined. Results:The content validity index was 0.65 and the content validity ratio was 0.89. Item 14 was removed from the skill domain because it was not related to the psychiatric ward. According to the results of factor analysis, 40 items and three domains of knowledge (6 items), attitude (14 items), and skills (20 items) were confirmed with acceptable values. In terms of its convergent validity, PSCSE had a moderate correlation (r = 0.57) with the Assessment of the Safe Nursing Care (ASNC) scale. The correlation coefficient for test-retest was ICC = 0.92 for the whole instrument and 0.89, 0.89, and 0.92 for the domains of knowledge, attitude, and skill, respectively. The internal consistency coefficient (Cronbach's alpha) of the whole tool was 0.95 and 0.95, 0.79, and 0. 95 for the domains of knowledge, attitude, and skill, respectievly. Conclusion: Persian version of the nurses' competency tool in ensuring patient safety in psychiatric wards has acceptable psychometric characteristics. Keywords: Validity, Reliability, Confirmatory factor analysis, Patient safety competency, psychiatric nurse