To provide a system for selling and buying intellectual property rights (especially, patent right and utility model right) which can calculate variation in selling price due to a decrease in market value depending upon the remaining period of the right and technical service life properly, not uniformly but according to respective right contents, and to provide a method, a program and a recording medium therefor.

When there is no application of a bid for the rights listed on the dealing market on the Internet 10, a server 22 at a Web site calculates the basic number of effective life days of the right to be sold every time a specified period elapses, finds an amount decrease rate corresponding to the number of days after the right is listed and the basic number of service life days of the right, calculates a new selling price from the amount decrease rate, and publishes the new selling price on the Internet 10.