A host computer stores stocked-product data and estimation data in an order placement and reception information database. In response to an inquiry request from the terminal, the host computer permits a terminal to refer to the stocked-product data and estimation data of parties relating to a relevant product distribution channel. The terminal refers to the data, creates estimation data, and transmits the estimation data to the host computer. The host computer stores the received estimation data in the order placement and reception information database as order placement data, and performs delivery management on the basis of the order placement data.