This research aimed at learning and analyzing the effectiveness of word of mouth toward customers’ interest in People’s Business Credit in Bank Syariah Mataram Branch, Lombok. The type of the research was associative quantitative approach using primary data in the form of observation and questionnaire obtained directly from saving customers. The hypothesis test in the research used MRS test (Moderation Regression Analysis) using SPSS25.The research result indicated that talking, promoting, and selling simultaneously and partially had positive and significant influence toward customers’ interest. The analysis result of the relation between the effectiveness approach connected to the dependent and independent variables was in an effective level with the value of 3,168. It can be concluded that word of mouth has a very effective level in People’s Business Credit in Bank Syariah.