Islamic Microfinance Institutions (IMI) have a strategic role with their main function being to collect funds from people with excess funds and channel the funds to people in need effectively and efficiently. The existence of IMI is expected to help people, especially those from the lower middle class, in gaining access to funding. However, the perception and attitude of the community towards bank interests and the profit sharing system show diversity. Some people still choose to accept interest and consider it the same as the profit sharing system, so an analysis of factors that influence the community's interest in using IMI products is needed. The purpose of this study was to determine the effect of knowledge, promotion, service quality, and religiosity on the community's interest in using IMI products in Lamongan. The sample used was 100 samples selected using the purposive sampling method. The data was processed using multiple linear regression analysis techniques. The test results stated that partially and simultaneously, the variables of knowledge, service quality, promotion, and religiosity had a positive effect on the community's interest in using IMI products in Lamongan.