This research was aimed at describing the customers’ response towards the conversion plan of NTB Bank from conventional system to sharia, and analyzing the support level and loyalty of the customers towards the conversion plan of NTB Bank. This research used qualitative and quantitative methods. The quantitative method was conducted with descriptive method to describe the percentage value of the loyalty and support level of the customers towards conversion plan of NTB Bank. The qualitative method was conducted to explain the reason why the customers were loyal and supporting the conversion plan of NTB Bank. The result of the research showed that from 90 respondents of NTB Bank that became sample had loyalty level of 91% and had support level of 92%, meaning that the customers of NTB Bank were dominant in terms of loyalty and supported the conversion policy of NTB Bank into sharia system. The loyalty of NTB Bank customers was caused by the bank customers needed sharia based bank as a transaction device for saving and loan. Meanwhile, the reason why the customers supported the conversion plan was, with sharia bank, the costumers were able to avoid the bank interest (usury).