To provide a user data copy/migration system of a terminal device which prevents falsification by a third party when the same data as the charged user data stored in the terminal is stored in another terminal.

The user data copy/migration system is equipped with first and second terminals connectable to communication means (10, 20) and a means (OTA system 30) to control the first and second terminals connected through the communication means. The first terminal stores data for its users, and the second terminal is equipped with a memory to store the user data. The control means is equipped with a means (memory 32) to temporarily store user data of the accessed first terminal, together with a means which makes only a terminal permitted beforehand accessible (authentication mechanism 31), and copies/migrates user data of this means to the accessed second terminal.