Each side sill of a vehicle body structure includes in addition to an outer panel (21) and an inner panel (22) jointly forming a closed cross section structure (23), a first stiffener (25) extending in the fore and aft direction and interposed between the outer panel and the inner panel and having a lower edge joined to the lower edges of the outer panel and the inner panel, a second stiffener (26) formed as a channel member extending in the fore and aft direction and having an open side facing in the inboard direction, the second stiffener having an upper edge and a lower edge attached to an outboard side of the first stiffener, and a third stiffener (27) extending in the fore and aft direction and in a transverse direction to have an outboard edge joined to the first stiffener and an inboard edge joined to the inner panel.