The loss of data stored in a secure memory card, such as a SIM card, due to the physical destruction thereof is prevented. A host unit performs card authentication of a memory card, and transmits update data for the memory card by security communication to update data when the result of the authentication is OK. Then, the host unit outputs a request for mirror-updating the card data to a base station server. When an access is permitted, the card data is transmitted to the base station server via the host unit to mirror-update the card data. When the mirror-updating of the card data is completed, the base station server returns a completion confirmation to the host unit, so that a data backup process is completed. By thus causing the base station server to mirror-update the data in the memory card, the loss of the stored data is prevented.