A project support system supports the smooth operation of a project. For each predetermined unit that a project comprises, a model case which prescribes a target for each consensus-building task, and an ideal execution time and execution method for each of the consensus-building tasks based on the performance of each consensus-building task executed in a previous project is generated. A consensus building plan which prescribes, for each of the predetermined units, a target, an execution time and an execution method for each of the consensus-building tasks which are to be executed in a current project based on information of the current project and the corresponding model case is generated.