To improve customer satisfaction level by setting a suitable price according to the actual sales volume of a commodity.

When a purchase applicant transmits commodity data by using a communication terminal 1, a server 2 having received the commodity data extracts, from a database, respective data for the material cost, the processing cost and the sales volume relating to the commodity specified by the commodity data to calculate the price of the commodity based on the extracted data. The data of the material cost varies depending on the total use quantity of the materials shared by a plurality of kinds of commodities, and the data of the sales volume of the commodity is updated to the latest data as required. Accordingly, the price of the commodity can be set based on the latest data at a receiving point of the commodity data, and the material cost according to the total use quantity of the materials shared by the plurality of kinds of commodities is considered in setting the price, so that the suitable price according to the actual sales volume of the commodity can be set and the customer satisfaction level can be improved.