1. An information processing system comprising: a first storage for storing an association information database in which association information is stored, said association information being information in which elements belonging to a plurality of element items in a one-to-one corresponding manner are associated with each other between said plurality of element items; an information extracting unit, in response to designation of an extraction condition of a user, for extracting partial association information corresponding to said extraction condition from said association information database; and a display for visibly outputting a view of network information in accordance with said partial association information, said network information being information in which a plurality of elements belonging to said plurality of element items are associated with each other between said plurality of element items so as to form a network.