To distribute an advertisement more suitable for each user.

In on-line advertisement distribution, when a plurality of advertisements are displayed in one impression, one advertisement is distributed for a predetermined time, and real-time bidding (RTB) is started for an advertisement display opportunity immediately before the end of the distribution. On the basis of user viewing possibility and user attention possibility, distribution time is measured by use of a viewable time (VT) in which contents are valid to a user.