To reduce uncertainties and make rational plans, the presumption of contingency against a failure of projects and an occurrence of unpredictable risks is important with accurate estimations as the work progressing. Therefore, if the presumption of contingency reflecting uncertainties carries out at a decision making point of time, be able to prepare for risks. The purpose of this paper is to present a management process of contingency through the performance analysis of project. In the cost planning phase, this study offers a process which is predictable contingency and predicts the range of fluctuation of the cost, laking an advantage of EVM in construction phase. With reflecting the results from this procedure, this study presents a process, rationally manageable contingency.