An information processing device is capable of handling changes occurring in values of information possessed by targets. Relationships between information are expressed as relationship structures through connection in a hierarchical manner using links expressing topic nodes expressing content of information as reference information. The relationship structures are generated for each provider providing information and generate an overall relationship structure for all of the information. A weighting is assigned to links so that values can be calculated for the topic nodes using just the weightings of nodes linking to topic nodes. These values are such that in a case where user information is utilized, topic node values relating to this information are added. It is therefore possible to know the value of information with respect to a user using these topic nodes.