There is provided a an apparatus for manufacturing a display device. An apparatus for manufacturing a display device comprises a body generating ultrasonic vibration; and a horn including a horn body portion connected to the body and amplifying the ultrasonic vibration and a horn tip portion connected to the horn body portion and applying the ultrasonic vibration onto a bonding object, wherein the horn body portion includes at least one body groove surrounded by the horn body portion and completely penetrating the horn body portion in a thickness direction from the surface of the horn body portion.