A switch is provided on a device main body. When the switch is switched to a permission state, authentication by a specific identification code (PIN code) is permitted. When the switch is switched to an inhibition state, the authentication by the specific identification code is inhibited. When the switch is normally set in the inhibition state, any access from an illicit user using the specific identification code can be prevented. Additionally, when a predetermined time has elapsed after the switch is set in the permission state, the authentication by the specific identification code is inhibited. With this arrangement, even when the user forgets to return the switch that has been set in the permission state to the inhibition state, any illicit access can be prevented, and the security for the device can be ensured.