To provide an enclosure determination method and an enclosure management system capable of enclosing an optimum advertising matter for a customer as an enclosure to be attached to a report, determining an enclosable amount of enclosures, and being usable by a company or family type store having no system of commodity sales or application on the Internet for advertisement/sales activities.

A data delivery server 3 extracts, on receipt of an access from a customer terminal 1, the information of a customer concerned from a customer DB 4, and also extracts information for transmittable enclosures from an enclosure DB 5 and presents it to the customer terminal 1. When the customer selects an enclosure, the data delivery server 3 calculates the weight of the report and enclosure to be transmitted, and displays whether or not it is within a predetermined weight. When the customer determines the selection, information for specifying the selected enclosure is registered in the customer DB 4. When an enclosure information processor 6 processes and delivers the information recorded in the customer DB 4 to an enclosing and sealing machine 9, the report and the enclosure are enclosed and sealed.