A data storage system comprises a temporary cache for temporarily storing data, a permanent cache for storing data for a predetermined period, and a memory selector for selectively having the temporary cache and the permanent cache store the data received by a terminal communicator. A data sorter sorts the data into temporary cache data to be stored in the temporary cache and permanent cache data to be stored in the permanent cache. In this way, it may be unnecessary to confirm whether or not the permanent cache data is updated in the permanent cache may be eliminated.