The coffee production potential in Rengganis Mountain Slope, Jember, East Java, Indonesia has not yet been optimally managed. This condition indicates the lack of harmony within the running system in the plantation sector in Jember. It is important to involve all related elements in a coffee agribusiness, either the main element or the supporting element, to solve the problem as the effort in developing coffee agribusiness in Rengganis Mountain Slope, Jember, East Java. The fact motivated a study with ISM method to map the problems, capture the key subjects and factors influenced the system as well as develop the institutional model to fix the current condition. This is a descriptive study with expert system approach. Sample was determined through purposive sampling by paying attention to the representation of each field or institution. The interview involved 5 experts, consisted of the experts from Indonesian Coffee and Cocoa Research Institute, Jember Office of Crop and Horticulture, Head of Plantation Counseling, Manager of a Private company, and a farmer. The data was processed by using dDSS V.1 PRE-NET application. The Interpretive Structural Modeling (ISM) analysis result showed that the main factor which drove the change of coffee agribusiness system was the synergy of business owner, farmers, and the government to solve the problems within the coffee agribusiness. The most urgent problem to solve was making a regulation which will benefit all parties. The suitable institutional model for the condition above was the involvement of the key subjects such as government, farmers, and private parties to collaborate through consultation and discussion. Thus, the farmer and business owner will be in the develop economic and social up grading equity