To give an indicator of which manufacturer, store, expert, etc., are trustful by calculating trust values in fields of consumption activities.

Bodies of consumption activities (web site, consumer, advertisement media, store, manufacturer, expert, etc.) and trust relations among the bodies are extracted from various information sources such as polling, a web page, a magazine, and an electronic bulletin board, and represented by a network chart including the bodies as nodes and the trust relations as arrows. The trust values are calculated by weighting the nodes and arrows. Based upon information on them, consumers are provided with information recommending and introducing articles and sellers are provided with effective marketing information.