In the present invention, processing for a service such as reducing the charges placed on electronic mail transmitted and received within a predetermined group is performed efficiently. An electronic mail charging system comprises: a user database storing information specifying a mobile communication terminal in association with the group ID of a group to which the terminal belongs; an ID comparison unit for detecting the transmission of an electronic mail from a transmission terminal to a reception terminal, obtaining information specifying the transmission terminal and reception terminal from the electronic mail, referring to the user database on the basis of this information, and comparing the group ID corresponding to the transmission terminal with the group ID corresponding to the reception terminal; and a charging server for generating charging information in order to place charges on the transmitted electronic mail on the basis of the result of this comparison.