The present invention relates to an apparatus and a method for updating firmware of an embedded controller (EC) constituted in portable machinery. Embodiments of the present invention can set identification information for maintaining a system power-on state before performing operations of updating the firmware of the embedded controller. In the ROM area of the embedded controller, a new firmware file is updated and recorded. Then, the new firmware file can be updated and recorded in the RAM area of the embedded controller after system re-start or while maintaining the system power and without system re-start responsive to the identification information.