PURPOSE: To select the security protection of a terminal equipment by operation of an operator when the terminal equipment is started.

CONSTITUTION: An EEPROM 2 of a terminal equipment includes a password storing area 3 and a security state storage area 4 which stores a lock or unlock state. The security state is unlocked simultaneously with storage of a password and then locked with a security lock instruction and with storage of a password and a password input screen is displayed, and a normal work screen is displayed when the security state is unlocked. In a display state of the password input screen, an input signal is collated with the stored password. If the coincidence is secured between the signal and the password, the security state is unlocked. If not, the lock state is kept until the coincidence is secured.