PURPOSE: To quickly perform the inquiry of the stock commodities and the transmission of ordering commands, etc., among the branch stores having data communication stations by providing a stock data control means, a stock inquiry processing means, a message communication processing means, etc., to each data communication station.

CONSTITUTION: In case a data communication station 10A inquires of a data communication station 10B about the stock quantity of commodities, the station code, the commodity codes, etc., of the station 10B are inputted via an input operation means 15A and transmitted to the station 10B via a stock inquiry processing means 13A, a transmission/reception means 17A, and a public telephone circuit network 3. These input data are given to a stock data control means 12B via a transmission/reception means 17B of the station 10B. Then the stock data on the inquired commodities are read out of a commodity stock data storing means 11B and sent to the station 10A via the means 17B and the network 3. At the same time, a commodity transmission message, if desired, is transmitted via the message communication process means 14A and 14B, etc. Thus it is possible to quickly perform the inquiry of the stock commodities and the transmission of ordering commands, etc., among the branch stores having the data communication stations.