An embodiment vehicle body includes a rear cross member unit disposed in a vehicle width direction and coupled to front portions of a pair of rear side members disposed at a rear portion of the vehicle body, a pair of side seal units respectively coupled to end portions of the rear cross member unit in a vehicle length direction, a front cross member unit coupled to front portions of the pair of side seal units in the vehicle width direction, an upper cross member unit coupled to upper portions of the pair of side seal units in the vehicle width direction, and a rear floor panel assembly connected to the rear cross member unit, the pair of side seal units, the front cross member unit, and the upper cross member unit.