A communication system preferable to a technique of allowing only an ISP (151) connecting a user terminal to the Internet to manage information about the charging for the service provided to the user by an ASP (132) in the Internet so as to prevent credit card information on the credit card of the user from leaking into the Internet and preferable to dial-up server for providing connection with access limit to a computer communication network such as the Internet to a terminal, a relay device, a service providing device, a relay method, a service providing method, and a program product for realizing them. The feasibility of the relay between a terminal (111) and an ASP (132)I by an ISP (151) is determined on the basis of the relay condition (for example, the condition determined by the IP address and the port number) correlated with the user using the terminal (111). The system inquires of the ISP (151) if the ASP (132) provides a service to the terminal (111). If the user of the terminal (111) is registered in the ISP (151), the ISP (151) carries out the charging of the service in place of the ASP (132), and the ASP (132) provides the service to the terminal (111) through the ISP (151).