A portable terminal with a body having a front surface with a display unit and rear surface including a rear password input device provided on a rear surface of the body, which is opposite to the display device, to receive a password for setting or releasing of use restriction, a storage device that stores the input password for the setting of the use restriction, and a control device that determines the releasing of the use restriction by comparing the password for the releasing of the use restriction, which is input into the rear password input device, with the stored password for the setting of the use restriction. The input of the password for the setting or the releasing of the use restriction is prevented from being exposed to other persons, so that the security of the portable terminal is remarkably improved.