There is provided means for identifying whether or not users of mobile information terminals (mobile information terminals) in a network service are the same as or different from one another. Location information 151, 152 is obtained by the mobile information terminals 121 each comprising a GPS function, and location information 151 representing a resident state at a home, a workplace or a school is obtained when the mobile information terminal users 123 carry their respective mobile information terminals 121. The location information 151 is specific to each user, and therefore, is used as identification information to differentiate the users to thereby allow identification of the users of the mobile information terminals by a management server 110.