Patent ID: 8085162

Claim:
A tamper prevention system comprising: a mounting unit; a portable terminal device detachably mounted to the mounting unit and comprising: an operation input unit that enables a user to input operation data; and a performing unit configured to perform an operation in accordance with the operation data; a first data input unit that enables the user to input first data; an authentication data storing unit that stores authentication data; an authentication unit that authenticates the user when the first data matches the authentication data; a detecting unit that detects whether or not the portable terminal device is removed from the mounting unit; and a setting unit that sets the performing unit to a first mode when the authenticating unit has authenticated the user, and that sets the performing unit to a second mode when the authenticating unit has failed to authenticate the user and the detecting unit has detected that the portable terminal device is removed from the mounting unit, wherein the performing unit performs the operation in accordance with the operation data when the setting unit sets the performing unit to the first mode, and fails to perform the operation in accordance with the operation data when the setting unit sets the performing unit to the second mode.