After the Second World War , Japan became an important world economic power , and has been famous for its distinctive "Japanese Management ." In Japanese decision process , a key characteristic is the building of consensus , and it is achieved through Nemawashi process . In this process, one person or a small group is assigned the role for coordinator. He works toward gaining a consensus among the participants by obtaining their views , carrying out negotiations and engaging in persuasion . Watabe , Holsapple and Whinston proposed a mathematical model to support the Nemawashi process .This model inherits the spirit of Multiple Criteria Decision Making (MCDM) and take the various aspects of participants into account . Through setting evalution criteria by expert and participants , it can help coordinator to select a decision plan . With the progress of technology , we can improve the effectiveness of individual or group decisionmaking by the support of computer information system . Thus , lots of different Decision Support System(or Group Decision Support System) are created to support decision-making . So , here , we take the concept of Decision Support System into the Nemawashi decision process . This reserch is based on the model , and then develops a Decision Support Syetem prototype to support the coordinator . Finally , we gather some case data to valid the system . The result of validation shows that there are good accuracy in various plan selection strategies , in addition to the functions of data base management and friendly user interface, this system may be considered a good tool for supporting the coordinator .