The invention discloses an engineer mode operating device and a method for a portable terminal. The method comprises that: a control unit of the portable terminal is started after operating power is supplied to control a timing unit at an idle state to calculate a predetermined time, when a main key signal is inputted in a key region unit, the control unit of the portable terminal activates and controls an engineer unit, when a latent key signal is inputted, an engineer mode is entered in. If the main key signal is not inputted before finishing the set predetermined time calculating, entering in the engineer mode is cutted radically. The invention increases the required security for entering in the engineer mode, operates the system successfully and inhance the reliability. |