A mobile terminal having detachably mounted thereon a recording medium in which user-specific information is written, and besides the recording medium, having terminal-specific information recorded thereon, the mobile terminal performing radio communication with the recording medium mounted thereon, including: a locking instruction determination section which determines whether or not announcement information transmitted to unspecified mobile terminals by radio communication is locking instruction information containing terminal-specific information to instruct locking of a mobile terminal specified by the terminal-specific information; a coincidence determination section which determines whether or not terminal-specific information contained in the locking instruction information coincides with that recorded on the mobile terminal; and a locking section which locks the mobile terminal to disable at least part of functions of the mobile terminal.