This invention provides a computer system capable of jointly delivering commodities not included in delivery plan information even after the delivery plan information is generated, and each base receives the generated delivery plan information, or a transport unit has made the round of each base. The computer system for realizing a delivery system which controls the transport unit to make the round of bases, thereby delivering commodities to the bases, includes a shipping base terminal, a reception base terminal, a transport terminal, and an information management computer, and the information management computer refers to attribute information of the commodities requested to be delivered to select commodities to replace with the commodities requested to be delivered from the commodities planned to be delivered, and corrects the delivery plan information.