There is provided an electro-mechanical brake with a differential gear. The electro-mechanical brake with a differential gear includes a driving unit that generates a rotational force by a power that is selectively applied along with the operation of the brake pedal by the user, a differential gear unit that is connected to the driving unit through a gear and in which a first shaft and a second shaft that are disposed in a straight line to serve as a rotational shaft are rotated in the same direction by the rotational force provided by the driving unit, an external braking unit that is connected to the first shaft of the differential gear unit through a gear to provide a braking power to an outer surface of the disc along with the rotation of the first shaft of the differential gear unit, and an internal braking unit that is connected to the second shaft of the differential gear unit through a gear to provide a braking power to an inner surface of the disc along with the rotation of the second shaft of the differential gear unit. When the driving unit is driven, the rotational force of the driving unit is transmitted to the differential gear unit, and the external braking unit and the internal braking unit that are connected to the differential gear unit simultaneously provide the braking powers to the disc along with the rotation of the differential gear unit.