A master management system includes a duty master creating part that counts the number of users in each group of same-attribute users who desire to use each of the applications, that identifies the applications each of which the number of users desiring to use is equal to or larger than a predetermined number, that creates and stores a master in a master management database of a storage device; and an individual setting part that identifies virtualization-possible applications of the applications each of which the number of users desiring to use is equal to or smaller than the predetermined number, and that sets data on users desiring to use the virtualization-possible applications in the distribution destination list of a distributing server.