A problem that a load on an affiliate server increases when an affiliate reward is divided among a plurality of people is solved. When a user purchases a commodity or receives service in an EC site, an affiliate reward dividing apparatus adds a full amount of a reward to one of a poster database and an introducer database on the basis of a dividing ratio stored in an affiliate database. A computation of referring to a dividing ratio for each reward and dividing a reward, and a process of accumulating a divided reward in each data base is not necessary, so that a load on a system can be lessened.