Islamic banks are financial institutions that have a wide market potential in Indonesia as one of the applications of the Islamic Islamic economic system in realizing Islamic values ​​and teachings that regulate the economic sector of the Ummah. The number of new financial institutions that have emerged as a Sharia Bank as a business entity is demanded to be able to compete with other financial institutions to survive and increase their profitability. One of the supporting factors for the development of Islamic banking is the public's interest in choosing financial institutions. This research was conducted with the aim of analyzing the influence of cultural and psychological factors partially and simultaneously on customer decisions in choosing Islamic banks at Bank Syariah Mandiri KCP Tajur. The data in this study are primary data obtained from distributing questionnaires to 100 customers of Bank Syariah Mandiri KCP Tajur. The analysis model used to test the hypothesis is simple linear regression with the t test method and the f test using the Statistical Package for the Social Sciences (SPSS) program. The results of the t test of this study indicate that cultural factors have no effect on customer decisions in choosing Bank Syariah Mandiri Tajur, while psychological factors affect customer decisions in choosing Bank Syariah Mandiri Tajur. The results of the F test of this study indicate that cultural and psychological factors have a significant effect on customer decisions in choosing Bank Syariah Mandiri Tajur.