A mobile terminal apparatus checks if a user is a proper user based on the operation of the user and, if the result of authentication is negative, uploads predetermined data, which is part of data stored in a memory, to a predetermined server. After the transmission is completed, the mobile terminal apparatus erases the uploaded data from the memory. It is also possible to instruct the mobile terminal apparatus to upload and erase data from an external source using an electronic mail or a telephone tone signal sequence. This may protect data contained in mobile terminal apparatus that has been lost, from a person who improperly attempts to access the data.