The reader/writer repeatedly reads data, which is stored in an IC tag existing in an area where communication with the reader/writer can be established, from the IC tag in a noncontact method. The reader/writer transmits the read data to the administrative device. The administrative device generates read data which shows the result of reading in chronologic order and generates feature data indicative of the feature of the result of reading on the basis of the generated time series data. An IC tag is sorted as a target tag or an unnecessary tag by sorting the read data as necessary data or unnecessary data on the basis of the generated feature data.