A vehicle seat back structure of one embodiment of the present invention comprises: a headrest; a seat back frame; a pad disposed at the front of the seat back frame; a back rest surface of the pad; and left and right side supports provided on both sides of the back rest surface in the seat width direction. The vehicle seat back structure is characterized in that a left slit and a right slit, which pass through in the thickness direction of the pad and extend vertically, are provided between the back rest surface and the left and right side supports, and the left and right slits are separated from each other in the seat width direction.