1. A product development process support system which analyzes dependencies between a plurality of requirements belonging to any of a plurality of layers in product development processes, the system comprising: input reception means for receiving input of information indicating the dependency between two requirements belonging to adjacent layers and of information indicating the degree of influence of the requirements on product development; and dependency derivation means for deriving the dependency between two arbitrary requirements belonging to the same layer from information indicating the dependencies between the two requirements in question and other requirements received by the input reception means and from information indicating the degree of influence of the two requirements in question, based on dependency derivation rules established in advance.