A method, device, system, and program for transaction of contents through a network are provided. In this transaction system, user terminals are configured to allow users to conduct transactions. A user sends a notification that the user hopes to register contents and prescribed items thereof in a data base in a center through the Internet. A Web server in the center registers the contents and the prescribed items thereof sent from the user in the data base. When use or transfer of the contents sent from the user occurs, a token according to the occurrence is sent to a user who hopes to use or transfer of the contents. In the case of accidents concerning contents and tokens, appropriation/compensation is implemented from funds for handling trouble to a user who suffers a loss of benefit. Thereby, it becomes possible to conduct transaction of contents easily and securely, spread around detail of contents extensively, and receive contents promptly which a user hopes to use.