Abstract: This study aims to investigate the cognitive dissonance of Muslim customers who have interest-bearing account in conventional bank. Cognitive dissonance is inconsistency between two cognitive elements that cause psychological discomfort such as depression, anxiety and stress, prevention of self-actualization and social connection with others and loss of sleep. This research design uses posttest control group design. The subject of experiment is Muslim customers who have interest-bearing account in conventional banking. The results showed that the Muslim customers who save in usurious banks and get information of prohibition of usury will experience cognitive dissonance. The phenomenon of cognitive dissonance of Muslim customers is opportunity for Islamic banking to increase its market share by cognitive consonance strategy. Consonance should be done by strengthening information of forbidden of usury and showing the alternative for reducing dissonance is only switching. In addition, Islamic banking should frame the information of forbidden of usury in logical and persuasive message. Besides that Islamic bank also facilitate customer switching by cheap of switching cost and excellent technical quality and service.