“Public Involvement” becomes a keyword in drafting comprehensive plan. However, it has been limited to putting together opinion by opening of workshop. There are no keys on this fact, when opinion of inhabitant can be accurately reflected. It is a problem of what is called “silent majority”. Based on these backgrounds, this study proposes Public Involvement support system. To begin with, this system utilizes AHP, and it is quantitatively clarified on feeling value of all participation members of workshop. In addition, member is grouped by utilization of cluster analysis using feeling value data. Then, by clarifying of allelism structure, convergence directivity of discussion is presented. By utilizing this system, it becomes possible that group consensus building is supported. And, it is possible to ease problem of the silent majority. In addition, the case of concretely utilizing this support system is presented. In 4th comprehensive plan decision in Hokkaido Siraoi town, this system is utilized in scene which presents directivity of “future image of community planning”. Then, a posteriori estimated result from inhabitant is analyzed for directivity of “future image of community planning”.