Until now, many studies for consensus building have been made. Recently, the study using AHP (Analytic Hierarchy Process) also mainly observed. In addition, this study proposes consensus building support system from the new viewpoint of “Alternative Adjustment” which was not considered ever since. This consensus building support system is a method for utilizing AHP, and it has possibility to clarify opposing structure of each member in group consensus building and directivity of alternative adjustment and the settlement solution is presented. And the alternative adjustment vector method is newly proposed as a method for formulating the directivity of the alternative adjustment.