Abstract: A system for remotely securing or locking a wireless information device is provided by sending an Email message with an attached password to the device. The owner of an information device specifies a password and a security level beforehand. The specified information is stored in a memory. When an electronic mail is received from another information device through a wireless telephone facility of the information device, a password attached to the electronic mail is checked with the password stored in the memory. When the password match occurs, a security process corresponding to the security level stored in the memory is executed. Security processes include processes of display screen lock, owner indication, and data erase. Thus, in the case where the information device should be lost or stolen, the leakage of data to others can be prevented.