An object of the present invention is to provide a vehicle body floor structure capable of effectively preventing deformation of a floor panel by increasing bending strength of the floor panel even when an upper reinforcing member of the floor panel is removed. A vehicle body floor structure of the present invention includes a dash cross member disposed along a kick-up portion on a lower surface side of a floor panel, a novel front side frame having an outer frame and an inner frame at a rear portion of a side frame body, and a floor panel on which beads are formed to form a closed cross-section in cooperation with the outer frame and the inner frame.