An embodiment door sealing structure of a monocoque type vehicle body having an overlap of a side inner panel, a side outer reinforce panel, and a side outer panel, and having a side seal panel and a side roof panel combined with the overlap, for providing a seal between a door opening of the vehicle body and a door frame mounted on the door opening is provided. An embodiment door sealing structure includes an insert flange formed toward a vehicle interior along an entirety of a boundary of the door opening over a plurality of joints interconnecting the side inner panel, the side seal panel, and the side roof panel and a first weather strip mounted on the insert flange and configured to form a seal between the vehicle interior and a vehicle exterior.