An electronic device, a control method thereof and a security program are provided which are capable of preventing or suppressing the theft of the electronic device.The electronic device comprises mounting means for loading a portable recording medium and encrypted information write means for encrypting predetermined information using an encryption key unique to the electronic device and writing the encrypted information in the recording medium. The electronic device further comprises encrypted information read means for reading the encrypted information recorded in the recording medium in the case where the recording medium is loaded in the mounting means, decryption execution means for executing the decryption of the encrypted information using the encryption key, and control means for setting the electronic device in usable mode in the case where the encrypted information is decrypted by the decryption execution means.